# data[].attributes.body
the color was different and the melting point makes the chemical change

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its X because x is every where and gas is all over the place has well.

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My answer is B because it had a chemical reaction.

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its B because ice cube do have smaller surface and heat do move to cold

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the answer is b because it has a chemical chang

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B

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model 2 and x

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low,medium,high

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hot plate off is low  hot plate 60 C is medium hot plate set to 120 C high.

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B is the answer.

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The color was different, the melting point was different as well.

# data[].attributes.body
B

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the answer is B

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B

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low,medium,high

# data[].attributes.body
model 2 and model x

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B

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the color was different and the melting point was different as well.

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The answer us B.

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b

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The color is not the same and the melting point is not the same.

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low, medium, high

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B

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the answer is B

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hot plate off is low pressure , hot plate 60 C is medium , hot plate set to 120 C high.

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B because it had a change.

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the answer is B because it had a chemcial reaction.

# data[].attributes.body
B.

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beaker 2

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B

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model 2 and model x

# data[].attributes.body
B.

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B

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B

# data[].attributes.body
beaker 2

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The type of matter effect the temperature of a substance is a liquid will be gas a solid will turn into a liquid.

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hot plate off is low pessure , hot plate 60 is medium , 127 plate is high

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B.

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Matter can exist in a solid, liquid or gaseous state, and the state a substance is in can be largely determined by its temperature. When a certain temperature threshold unique to each substance in the universe is crossed, a phase change will result, changing the state of the matter. Under conditions of constant pressure temperature is the primary determinant of a substance's phase. The differential in temperatures and the phases of different kinds of matter allows for the operation of heat engines and refrigerators.

TL;DR (Too Long; Didn't Read)

Temperature has a direct effect on whether a substance exists as a solid, liquid or gas. Generally, increasing the temperature turns solids into liquids and liquids into gases; reducing it turns gases into liquids and liquids into solids.

At low temperatures, molecular motion decreases and substances have less internal energy. Atoms will settle into low energy states relative to one another and move very little, which is characteristic of solid matter. As temperatures increase, additional heat energy is applied to the constituent parts of a solid, which causes additional molecular motion. Molecules begin to push against one another and the overall volume of a substance increases. At this point, the matter has entered the liquid state. A gaseous state exists when molecules have absorbed so much heat energy due to increased temperatures that they are free to move around one another at high speeds.

The point at which matter subjected to a particular temperature under conditions of constant pressure begins to change its phase is called the phase change threshold. At this temperature, every bit of the substance exposed to the heat will change its state. A shift from to a solid to a liquid occurs at the melting point, and the transition from a liquid to a gas takes place at the boiling point. Conversely, the moment of change from a gas to a liquid is the condensation point and the shift from a liquid to a solid takes place at the freezing point.

A substance may undergo phase change from a solid to a gas or from a gas to a solid if the temperature it is exposed to is changed very quickly. If the temperature around a solid is raised very quickly, it can sublimate, or phase change from a solid to a gas without existing as a liquid. In the opposite direction, a gas that is suddenly supercooled can undergo complete deposition.

If pressure is constant, the state of a substance will depend entirely on the temperature it is exposed to. For this reason, ice melts if taken out of a freezer and water boils out of a pot if left at too high a temperature for too long. Temperature is merely a measurement of the amount of heat energy present in the surroundings. When a substance is placed in surroundings of a different temperature, heat is exchanged between the substance and the surroundings, causing both to achieve an equilibrium temperature. So when an ice cube is exposed to heat, its water molecules absorb heat energy from the surrounding atmosphere and begin to move more energetically, causing the water ice to melt into liquid water.

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What Is the Effect of Temperature on States of Matter?

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Matter can exist in a solid, liquid or gaseous state, and the state a substance is in can be largely determined by its temperature. When a certain temperature threshold unique to each substance in the universe is crossed, a phase change will result, changing the state of the matter.

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the answer is B.

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Effects of Temperature and Pressure on Matter | iKen | iKen Edu | iKen App

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Temperature has a direct effect on whether a substance exists as a solid liquid or gas . Generally, increasing the temperature turns solids into liquids and liquids into gases .

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Changes of State | Matter |  Physics | FuseSchool

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Like matter, energy comes in different types.result in the transfer of kinetic (thermal) energy from the hotter to the cooler matter.

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3 States of Matter for Kids (Solid, Liquid, Gas): Science for Children - FreeSchool

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Three States of Matter

The three states of matter are the distinct physical forms that matter can take: solid, liquid, and gas.

Learning Objectives

Describe the three states of matter

Key Takeaways

Key Points

Matter can exist in one of three main states: solid, liquid, or gas.

Solid matter is composed of tightly packed particles. A solid will retain its shape; the particles are not free to move around.

Liquid matter is made of more loosely packed particles. It will take the shape of its container. Particles can move about within a liquid, but they are packed densely enough that volume is maintained.

Gaseous matter is composed of particles packed so loosely that it has neither a defined shape nor a defined volume. A gas can be compressed.

Key Terms

liquid: A substance that flows and keeps no definite shape because its molecules are loosely packed and constantly moving. It takes the shape of its container but maintains constant volume.

gas: A substance that can only be contained if it is fully surrounded by a container (or held together by gravitational pull); a substance whose molecules have negligible intermolecular interactions and can move freely.

solid: A substance that retains its size and shape without a container; a substance whose molecules cannot move freely except to vibrate.

The three states of matter are the three distinct physical forms that matter can take in most environments: solid, liquid, and gas. In extreme environments, other states may be present, such as plasma, Bose-Einstein condensates, and neutron stars. Further states, such as quark-gluon plasmas, are also believed to be possible. Much of the atomic matter of the universe is hot plasma in the form of rarefied interstellar medium and dense stars.

Historically, the states of matter were distinguished based on qualitative differences in their bulk properties. Solid is the state in which matter maintains a fixed volume and shape; liquid is the state in which matter adapts to the shape of its container but varies only slightly in volume; and gas is the state in which matter expands to occupy the volume and shape of its container. Each of these three classical states of matter can transition directly into either of the other two classical states.

Solids

A solid's particles are packed closely together. The forces between the particles are strong enough that the particles cannot move freely; they can only vibrate. As a result, a solid has a stable, definite shape and a definite volume. Solids can only change shape under force, as when broken or cut.

In crystalline solids, particles are packed in a regularly ordered, repeating pattern. There are many different crystal structures, and the same substance can have more than one structure. For example, iron has a body-centered cubic structure at temperatures below 912 °C and a face-centered cubic structure between 912 and 1394 °C. Ice has fifteen known crystal structures, each of which exists at a different temperature and pressure.

A solid can transform into a liquid through melting, and a liquid can transform into a solid through freezing. A solid can also change directly into a gas through a process called sublimation.

Liquids

A liquid is a fluid that conforms to the shape of its container but that retains a nearly constant volume independent of pressure. The volume is definite (does not change) if the temperature and pressure are constant. When a solid is heated above its melting point, it becomes liquid because the pressure is higher than the triple point of the substance. Intermolecular (or interatomic or interionic) forces are still important, but the molecules have enough energy to move around, which makes the structure mobile. This means that a liquid is not definite in shape but rather conforms to the shape of its container. Its volume is usually greater than that of its corresponding solid (water is a well-known exception to this rule). The highest temperature at which a particular liquid can exist is called its critical temperature.

A liquid can be converted to a gas through heating at constant pressure to the substance's boiling point or through reduction of pressure at constant temperature. This process of a liquid changing to a gas is called evaporation.

Gases

Gas molecules have either very weak bonds or no bonds at all, so they can move freely and quickly. Because of this, not only will a gas conform to the shape of its container, it will also expand to completely fill the container. Gas molecules have enough kinetic energy that the effect of intermolecular forces is small (or zero, for an ideal gas), and they are spaced very far apart from each other; the typical distance between neighboring molecules is much greater than the size of the molecules themselves.

A gas at a temperature below its critical temperature can also be called a vapor. A vapor can be liquefied through compression without cooling. It can also exist in equilibrium with a liquid (or solid), in which case the gas pressure equals the vapor pressure of the liquid (or solid).

A supercritical fluid (SCF) is a gas whose temperature and pressure are greater than the critical temperature and critical pressure. In this state, the distinction between liquid and gas disappears. A supercritical fluid has the physical properties of a gas, but its high density lends it the properties of a solvent in some cases. This can be useful in several applications. For example, supercritical carbon dioxide is used to extract caffeine in the manufacturing of decaffeinated coffee.

Phase Changes: What does a phase change look like at the molecular level? This video takes a look at the molecular structure of solids, liquids, and gases and examines how the kinetic energy of the particles changes. The video also discusses melting, vaporization, condensation, and freezing.

Substances and Mixtures

Substances are composed of pure elements or chemically bonded elements, whereas mixtures are composed of non-bonded substances.

Learning Objectives

Distinguish chemical substances from mixtures

Key Takeaways

Key Points

Matter can be broken down into two categories: pure substances and mixtures. Pure substances are further broken down into elements and compounds. Mixtures are physically combined structures that can be separated into their original components.

A chemical substance is composed of one type of atom or molecule.

A mixture is composed of different types of atoms or molecules that are not chemically bonded.

A heterogeneous mixture is a mixture of two or more chemical substances where the various components can be visually distinguished.

A homogeneous mixture is a type of mixture in which the composition is uniform and every part of the solution has the same properties.

Various separation techniques exist in order to separate matter, including include distillation, filtration, evaporation and chromatography. Matter can be in the same phase or in two different phases for this separation to take place.

Key Terms

mixture: Something that consists of diverse, non-bonded elements or molecules.

element: A chemical substance that is made up of a particular kind of atom and cannot be broken down or transformed by a chemical reaction.

substance: A form of matter that has constant chemical composition and characteristic properties. It is composed of one type of atom or molecule.

Chemical Substances

In chemistry, a chemical substance is a form of matter that has constant chemical composition and characteristic properties. It cannot be separated into components without breaking chemical bonds. Chemical substances can be solids, liquids, gases, or plasma. Changes in temperature or pressure can cause substances to shift between the different phases of matter.

An element is a chemical substance that is made up of a particular kind of atom and hence cannot be broken down or transformed by a chemical reaction into a different element. All atoms of an element have the same number of protons, though they may have different numbers of neutrons and electrons.

A pure chemical compound is a chemical substance that is composed of a particular set of molecules or ions that are chemically bonded. Two or more elements combined into one substance through a chemical reaction, such as water, form a chemical compound. All compounds are substances, but not all substances are compounds. A chemical compound can be either atoms bonded together in molecules or crystals in which atoms, molecules or ions form a crystalline lattice. Compounds made primarily of carbon and hydrogen atoms are called organic compounds, and all others are called inorganic compounds. Compounds containing bonds between carbon and a metal are called organometallic compounds.

Chemical substances are often called 'pure' to set them apart from mixtures. A common example of a chemical substance is pure water; it always has the same properties and the same ratio of hydrogen to oxygen whether it is isolated from a river or made in a laboratory. Other chemical substances commonly encountered in pure form are diamond (carbon), gold, table salt (sodium chloride), and refined sugar (sucrose). Simple or seemingly pure substances found in nature can in fact be mixtures of chemical substances. For example, tap water may contain small amounts of dissolved sodium chloride and compounds containing iron, calcium, and many other chemical substances. Pure distilled water is a substance, but seawater, since it contains ions and complex molecules, is a mixture.

Chemical Mixtures

A mixture is a material system made up of two or more different substances, which are mixed but not combined chemically. A mixture refers to the physical combination of two or more substances in which the identities of the individual substances are retained. Mixtures take the form of alloys, solutions, suspensions, and colloids.

Heterogeneous Mixtures

A heterogeneous mixture is a mixture of two or more chemical substances (elements or compounds), where the different components can be visually distinguished and easily separated by physical means. Examples include:

mixtures of sand and water

mixtures of sand and iron filings

a conglomerate rock

water and oil

a salad

trail mix

mixtures of gold powder and silver powder

Homogenous Mixtures

A homogeneous mixture is a mixture of two or more chemical substances (elements or compounds), where the different components cannot be visually distinguished. Often separating the components of a homogeneous mixture is more challenging than separating the components of a heterogeneous mixture.

Distinguishing between homogeneous and heterogeneous mixtures is a matter of the scale of sampling. On a small enough scale, any mixture can be said to be heterogeneous, because a sample could be as small as a single molecule. In practical terms, if the property of interest is the same regardless of how much of the mixture is taken, the mixture is homogeneous.

A mixture's physical properties, such as its melting point, may differ from those of its individual components. Some mixtures can be separated into their components by physical (mechanical or thermal) means.

Classifying Matter (3 parts): Introduction to classifying matter as a substance or a mixture of substances. Mixtures are described as heterogeneous or homogeneous. Three common methods of separation are described.

Elements and Compounds

An element is a material that consists of a single type of atom, while a compound consists of two or more types of atoms.

Learning Objectives

Differentiate between elements and compounds and explore separation techniques

Key Takeaways

Key Points

Elements are the simplest complete chemical substances. Each element corresponds to a single entry on the periodic table. An element is a material that consists of a single type of atom. Each atom type contains the same number of protons.

Chemical bonds link elements together to form more complex molecules called compounds. A compound consists of two or more types of elements held together by covalent or ionic bonds.

Elements cannot be divided into smaller units without large amounts of energy. Compounds, on the other hand, can have their bonds broken with practical amounts of energy, such as the heat from a fire.

Matter can be broken down into two categories: pure substances and mixtures. Pure substances are further broken down into elements and compounds. Mixtures are physically combined structures that can be separated back into their original components.

Key Terms

element: Any one of the simplest chemical substances that cannot be changed in a chemical reaction or by any chemical means. Made up of atoms that all have the same number of protons.

chemical bond: Any of several attractive forces that serve to bind atoms together to form molecules.

compound: A substance made from two or more elements. Consists of a fixed ratio of chemically bonded atoms. Has unique properties that are different from the properties of its individual elements.

Elements

A chemical element is a pure substance that consists of one type of atom. Each atom has an atomic number, which represents the number of protons that are in the nucleus of a single atom of that element. The periodic table of elements is ordered by ascending atomic number.

The chemical elements are divided into the metals, the metalloids, and the non-metals. Metals, typically found on the left side of the periodic table, are:

often conductive to electricity

malleable

shiny

sometimes magnetic.

Aluminum, iron, copper, gold, mercury and lead are metals.

In contrast, non-metals, found on the right side of the periodic table (to the right of the staircase), are:

typically not conductive

not malleable

dull (not shiny)

not magnetic.

Examples of elemental non-metals include carbon and oxygen.

Metalloids have some characteristics of metals and some characteristics of non-metals. Silicon and arsenic are metalloids.

As of November, 2011, 118 elements have been identified (the most recently identified was ununseptium, in 2010). Of these 118 known elements, only the first 98 are known to occur naturally on Earth. The elements that do not occur naturally on Earth are the synthetic products of man-made nuclear reactions. 80 of the 98 naturally-occurring elements are stable; the rest are radioactive, which means they decay into lighter elements over timescales ranging from fractions of a second to billions of years.

Hydrogen and helium are by far the most abundant elements in the universe. However, iron is the most abundant element (by mass) in the composition of the Earth, and oxygen is the most common element in the layer that is the Earth's crust.

Although all known chemical matter is composed of these elements, chemical matter itself constitutes only about 15% of the matter in the universe. The remainder is dark matter, a mysterious substance that is not composed of chemical elements. Dark matter lacks protons, neutrons, or electrons.

Compounds

Pure samples of isolated elements are uncommon in nature. While the 98 naturally occurring elements have all been identified in mineral samples from the Earth's crust, only a small minority of them can be found as recognizable, relatively pure minerals. Among the more common of such "native elements" are copper, silver, gold, and sulfur. Carbon is also commonly found in the form of coal, graphite, and diamonds. The noble gases (e.g., neon) and noble metals (e.g., mercury) can also be found in their pure, non-bonded forms in nature. Still, most of these elements are found in mixtures.

When two distinct elements are chemically combined-i.e., chemical bonds form between their atoms-the result is called a chemical compound. Most elements on Earth bond with other elements to form chemical compounds, such as sodium (Na) and Chloride (Cl), which combine to form table salt (NaCl). Water is another example of a chemical compound. The two or more component elements of a compound can be separated through chemical reactions.

Chemical compounds have a unique and defined structure, which consists of a fixed ratio of atoms held together in a defined spatial arrangement by chemical bonds. Chemical compounds can be:

molecular compounds held together by covalent bonds

salts held together by ionic bonds

intermetallic compounds held together by metallic bonds

complexes held together by coordinate covalent bonds.

Pure chemical elements are not considered chemical compounds, even if they consist of diatomic or polyatomic molecules (molecules that contain only multiple atoms of a single element, such as H ₂ or S ₈).

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The three states of matter are the distinct physical forms that matter can take: solid, liquid, and gas. Describe the three states of matter Key Points Matter can exist in one of three main states: solid, liquid, or gas. Solid matter is composed of tightly packed particles.

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Why Temperature Remains Constant during a Phase Change

By Steven Holzner

Thanks to physics, we know that p hase changes occur when materials change state, going from liquid to solid (as when water freezes), solid to liquid (as when rocks melt into lava), liquid to gas (as when you boil water for tea), and so on. When the material in question changes to a new state - liquid, solid, or gas (you can also factor in a fourth state: plasma, a superheated gas-like state) - some heat goes into or comes out of the process without changing the temperature.

You can even have solids that turn directly into gas. As dry ice (frozen carbon dioxide gas) gets warmer, it turns into carbon dioxide gas. This process is called sublimation.

Imagine you're calmly drinking your lemonade at an outdoor garden party. You grab some ice to cool your lemonade, and the mixture in your glass is now half ice, half lemonade (which you can assume has the same specific heat as water), with a temperature of exactly 0 degrees Celsius.

As you hold the glass and watch the action, the ice begins to melt - but the contents of the glass don't change temperature. Why? The heat (thermal energy) going into the glass from the outside air is melting the ice, not warming the mixture up. So does this make the equation for heat energy

useless? Not at all - it just means that the equation doesn't apply for a phase change.

If you graph the heat added to a system versus the system's temperature, the graph usually slopes upward; adding heat increases temperature. However, the graph levels out during phase changes, because on a molecular level, making a substance change state requires energy. After all the material has changed state, the temperature can rise again.

Imagine that someone has taken a bag of ice and thoughtlessly put it on the stove. Before it hit the stove, the ice was at a temperature below freezing (-5 degrees Celsius), but being on the stove is about to change that. You can see the change taking place in graph form in the figure. (The specific heat of ice is around 2.1 x 10 ³ J/kg-C)

that the temperature of the ice will increase linearly as you add more heat to it, as you see in the graph.

However, when the ice reaches 0 degrees Celsius, the ice is getting too warm to hold its solid state, and it begins to melt, undergoing a phase change. When you melt ice, breaking up the crystalline ice structure requires energy, and the energy needed to melt the ice is supplied as heat. That's why the graph in the figure levels off in the middle - the ice is melting. You need heat to make the ice change phase to water, so even though the stove adds heat, the temperature of the ice doesn't change as it melts.

As you watch the bag of ice on the stove, however, you note that all the ice eventually melts into water. Because the stove is still adding heat, the temperature begins to rise, which you see in the figure. The stove adds more and more heat to the water, and in time, the water starts to bubble. "Aha," you think. "Another phase change." And you're right: The water is boiling and becoming steam. The bag holding the ice seems pretty resilient, and it expands while the water turns to steam.

You measure the temperature of the water. Fascinating - although the water boils, turning into steam, the temperature doesn't change. Once again, you need to add heat to incite a phase change - this time from water to steam. You can see in the figure that as you add heat, the water boils, but the temperature of that water doesn't change.

What's going to happen next, as the bag swells to an enormous volume? You never get to find out, because the bag finally explodes.

About the Book Author

Steven Holzner, PhD, was a contributing editor at PC Magazine and was on the faculty of both MIT and Cornell University. He wrote Physics II For Dummies, Physics Essentials For Dummies, and Quantum Physics For Dummies.

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Why Temperature Remains Constant during a Phase Change - dummies

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Thanks to physics, we know that phase changes occur when materials change state, going from liquid to solid (as when water freezes), solid to liquid (as when rocks melt into lava), liquid to gas (as when you boil water for tea), and so on. When the material in question changes to a new state - [...]

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What is heat? How does heat transfer take place? What are the effects on matter when heat transfers from one body to another? Here's what you need to know:

Heat Transfer Definition

Heat transfer is a process by which internal energy from one substance transfers to another substance. Thermodynamics is the study of heat transfer and the changes that result from it. An understanding of heat transfer is crucial to analyzing a thermodynamic process, such as those that take place in heat engines and heat pumps.

Forms of Heat Transfer

Under the kinetic theory, the internal energy of a substance is generated from the motion of individual atoms or molecules. Heat energy is the form of energy which transfers this energy from one body or system to another. This heat transfer can take place in a number of ways:

Conduction is when heat flows through a heated solid through a heat current moving through the material. You can observe conduction when heating a stove burner element or a bar of metal, which goes from red hot to white hot.

Convection is when heated particles transfer heat to another substance, such as cooking something in boiling water.

Radiation is when heat is transferred through electromagnetic waves, such as from the sun. Radiation can transfer heat through empty space, while the other two methods require some form of matter-on-matter contact for the transfer.

In order for two substances to affect each other, they must be in thermal contact with each other. If you leave your oven open while turned on and stand several feet in front of it, you are in thermal contact with the oven and can feel the heat it transfers to you (by convection through the air).

Normally, of course, you do not feel the heat from the oven when you're several feet away and that is because the oven has thermal insulation to keep the heat inside of it, thus preventing thermal contact with the outside of the oven. This is of course not perfect, so if you stand nearby you do feel some heat from the oven.

Thermal equilibrium is when two items that are in thermal contact no longer transfer heat between them.

Effects of Heat Transfer

The basic effect of heat transfer is that the particles of one substance collide with the particles of another substance. The more energetic substance will typically lose internal energy (i.e. "cool down") while the less energetic substance will gain internal energy (i.e. "heat up").

The most blatant effect of this in our day-to-day life is a phase transition, where a substance changes from one state of matter to another, such as ice melting from a solid to a liquid as it absorbs heat. The water contains more internal energy (i.e. the water molecules are moving around faster) than in the ice.

In addition, many substances go through either thermal expansion or thermal contraction as they gain and lose internal energy. Water (and other liquids) often expands as it freezes, which anyone who has put a drink with a cap in the freezer for too long has discovered.

Heat Capacity

The heat capacity of an object helps define how that object's temperature responds to absorbing or transmitting heat. Heat capacity is defined as the change in heat divided by the change in temperature.

Laws of Thermodynamics

Heat transfer is guided by some basic principles which have become known as the laws of thermodynamics, which define how heat transfer relates to work done by a system and place some limitations on what it is possible for a system to achieve.

Edited by Anne Marie Helmenstine, Ph.D.

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What You Need to Understand About Heat Transfer

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What is heat? How does heat transfer take place? What are the effects on matter when heat transfers from one body to another? Here's what you need to know: Heat transfer is a process by which internal energy from one substance transfers to another substance.

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A substance's state of matter is an extrinsic property, meaning it can be changed by its environment.

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Physical and Chemical Properties of Matter

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Changes of State | Matter |  Physics | FuseSchool

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A liquid is defined as fluid matter having no fixed shape but a fixed volume; it is one of the three states of matter. A liquid has the ability to flow as well as take the shape of a container. At the same time, it resists compression and maintains a fairly constant density. Given that temperature directly affects the kinetic energy of molecules in a liquid, the effects of temperature on liquids can be described in terms of kinetic-molecular theory.

Heat

An increase in the temperature of a liquid causes an increase in the average speed of its molecules. As the temperature of a liquid increases, the molecules move faster thereby increasing the liquid's kinetic energy. Furthermore, the higher the temperature of the liquid, the lower the viscosity since an increase in kinetic energy reduces the forces of intermolecular attraction. Viscosity is the quantity that describes a fluid's resistance to flow. Since kinetic energy is directly proportional to temperature, a liquid that is heated sufficiently forms a gas. This property can be shown in experiments by heating liquids. A Bunsen burner is one of the most commonly used methods of heating liquids in science labs.

Cold

As the temperature of a liquid falls, the speed of its molecules slows down. Since the molecular speed slows down, the kinetic energy reduces as well, thereby increasing intermolecular attraction of the liquid. This attraction in turn makes the fluid more viscous because viscosity is inversely proportional to the temperature of a fluid. Therefore, if a liquid is cooled sufficiently, it will likely crystallize, changing to its solid form. This property can be shown in a simple experiment involving a freezer and different types of liquids.

Temperature

The density of a liquid is affected by change in temperature. Increasing the temperature generally decreases its density and vice versa. During experimentation, with regard to volume, liquids generally expand when heated and contract when cooled. In simpler terms, liquids increase in volume with substantial increase in temperature and decrease in volume with significant decrease in temperature. A notable exception, however, is water that has a temperature between 0 °C and 4 °C.

Transition States

During the experiments, when the liquid's temperature is altered, the liquid undergoes certain transformations that affect its state of existence. For instance, when a liquid is heated, it will evaporate and change into a gaseous state. The point where a liquid changes into gas is known as its boiling point. When the temperature is lowered to a level where the liquid crystallizes and becomes a solid, the point where it changes its state is known as its freezing point.

About the Author

Steve Johnson is an avid and passionate writer with more than five years of experience. He's written for several industries, including health, dating and Internet marketing, as well as for various websites. He holds a bachelor's degree from the University of Texas.

Photo Credits

Beaker With Blue Liquid image by explicitly from Fotolia.com

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Science Project: The Effects of Temperature on Liquids

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A liquid is defined as fluid matter having no fixed shape but a fixed volume; it is one of the three states of matter. A liquid has the ability to flow as well as take the shape of a container. At the same time, it resists compression and maintains a fairly constant density.

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Changes of State | Matter |  Physics | FuseSchool

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Copyright © 2020 Multiply Media, LLC. All Rights Reserved. The material on this site can not be reproduced, distributed, transmitted, cached or otherwise used, except with prior written permission of Multiply.

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How heat energy affects the motion of particles? - Answers

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When heat is added to particles. The particles start to get heated which forces them to move at a greater speed then before, when you add heat to the particles they speed up and move faster. If you make particles colder then they will move at a slower speed.

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Flinn Scientific Best Practices for Teaching Chemistry Video Series

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Types of Chemical Reactions Lab with Worksheet & Answers

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Sparks fly in the reaction of zinc and sulfur! This video is part of the Flinn Scientific Best Practices for Teaching Chemistry Video Series, a collection of over 125 hours of free professional development training for chemistry teachers - http://elearning.flinnsci.com ATTENTION: This demonstration is intended for and should only be performed by certified science instructors in a safe laboratory/classroom setting.

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Brianna picture

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Brianna video

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A liquid is defined as fluid matter having no fixed shape but a fixed volume; it is one of the three states of matter. A liquid has the ability to flow as well as take the shape of a container. At the same time, it resists compression and maintains a fairly constant density. Given that temperature directly affects the kinetic energy of molecules in a liquid, the effects of temperature on liquids can be described in terms of kinetic-molecular theory.

Heat

An increase in the temperature of a liquid causes an increase in the average speed of its molecules. As the temperature of a liquid increases, the molecules move faster thereby increasing the liquid's kinetic energy. Furthermore, the higher the temperature of the liquid, the lower the viscosity since an increase in kinetic energy reduces the forces of intermolecular attraction. Viscosity is the quantity that describes a fluid's resistance to flow. Since kinetic energy is directly proportional to temperature, a liquid that is heated sufficiently forms a gas. This property can be shown in experiments by heating liquids. A Bunsen burner is one of the most commonly used methods of heating liquids in science labs.

Cold

As the temperature of a liquid falls, the speed of its molecules slows down. Since the molecular speed slows down, the kinetic energy reduces as well, thereby increasing intermolecular attraction of the liquid. This attraction in turn makes the fluid more viscous because viscosity is inversely proportional to the temperature of a fluid. Therefore, if a liquid is cooled sufficiently, it will likely crystallize, changing to its solid form. This property can be shown in a simple experiment involving a freezer and different types of liquids.

Temperature

The density of a liquid is affected by change in temperature. Increasing the temperature generally decreases its density and vice versa. During experimentation, with regard to volume, liquids generally expand when heated and contract when cooled. In simpler terms, liquids increase in volume with substantial increase in temperature and decrease in volume with significant decrease in temperature. A notable exception, however, is water that has a temperature between 0 °C and 4 °C.

Transition States

During the experiments, when the liquid's temperature is altered, the liquid undergoes certain transformations that affect its state of existence. For instance, when a liquid is heated, it will evaporate and change into a gaseous state. The point where a liquid changes into gas is known as its boiling point. When the temperature is lowered to a level where the liquid crystallizes and becomes a solid, the point where it changes its state is known as its freezing point.

About the Author

Steve Johnson is an avid and passionate writer with more than five years of experience. He's written for several industries, including health, dating and Internet marketing, as well as for various websites. He holds a bachelor's degree from the University of Texas.

Photo Credits

Beaker With Blue Liquid image by explicitly from Fotolia.com

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Science Project: The Effects of Temperature on Liquids

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A liquid is defined as fluid matter having no fixed shape but a fixed volume; it is one of the three states of matter. A liquid has the ability to flow as well as take the shape of a container. At the same time, it resists compression and maintains a fairly constant density.

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Why Temperature Remains Constant during a Phase Change

By Steven Holzner

Thanks to physics, we know that p hase changes occur when materials change state, going from liquid to solid (as when water freezes), solid to liquid (as when rocks melt into lava), liquid to gas (as when you boil water for tea), and so on. When the material in question changes to a new state - liquid, solid, or gas (you can also factor in a fourth state: plasma, a superheated gas-like state) - some heat goes into or comes out of the process without changing the temperature.

You can even have solids that turn directly into gas. As dry ice (frozen carbon dioxide gas) gets warmer, it turns into carbon dioxide gas. This process is called sublimation.

Imagine you're calmly drinking your lemonade at an outdoor garden party. You grab some ice to cool your lemonade, and the mixture in your glass is now half ice, half lemonade (which you can assume has the same specific heat as water), with a temperature of exactly 0 degrees Celsius.

As you hold the glass and watch the action, the ice begins to melt - but the contents of the glass don't change temperature. Why? The heat (thermal energy) going into the glass from the outside air is melting the ice, not warming the mixture up. So does this make the equation for heat energy

useless? Not at all - it just means that the equation doesn't apply for a phase change.

If you graph the heat added to a system versus the system's temperature, the graph usually slopes upward; adding heat increases temperature. However, the graph levels out during phase changes, because on a molecular level, making a substance change state requires energy. After all the material has changed state, the temperature can rise again.

Imagine that someone has taken a bag of ice and thoughtlessly put it on the stove. Before it hit the stove, the ice was at a temperature below freezing (-5 degrees Celsius), but being on the stove is about to change that. You can see the change taking place in graph form in the figure. (The specific heat of ice is around 2.1 x 10 ³ J/kg-C)

that the temperature of the ice will increase linearly as you add more heat to it, as you see in the graph.

However, when the ice reaches 0 degrees Celsius, the ice is getting too warm to hold its solid state, and it begins to melt, undergoing a phase change. When you melt ice, breaking up the crystalline ice structure requires energy, and the energy needed to melt the ice is supplied as heat. That's why the graph in the figure levels off in the middle - the ice is melting. You need heat to make the ice change phase to water, so even though the stove adds heat, the temperature of the ice doesn't change as it melts.

As you watch the bag of ice on the stove, however, you note that all the ice eventually melts into water. Because the stove is still adding heat, the temperature begins to rise, which you see in the figure. The stove adds more and more heat to the water, and in time, the water starts to bubble. "Aha," you think. "Another phase change." And you're right: The water is boiling and becoming steam. The bag holding the ice seems pretty resilient, and it expands while the water turns to steam.

You measure the temperature of the water. Fascinating - although the water boils, turning into steam, the temperature doesn't change. Once again, you need to add heat to incite a phase change - this time from water to steam. You can see in the figure that as you add heat, the water boils, but the temperature of that water doesn't change.

What's going to happen next, as the bag swells to an enormous volume? You never get to find out, because the bag finally explodes.

About the Book Author

Steven Holzner, PhD, was a contributing editor at PC Magazine and was on the faculty of both MIT and Cornell University. He wrote Physics II For Dummies, Physics Essentials For Dummies, and Quantum Physics For Dummies.

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Why Temperature Remains Constant during a Phase Change - dummies

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Thanks to physics, we know that phase changes occur when materials change state, going from liquid to solid (as when water freezes), solid to liquid (as when rocks melt into lava), liquid to gas (as when you boil water for tea), and so on. When the material in question changes to a new state - [...]

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Matter can exist in a solid, liquid or gaseous state, and the state a substance is in can be largely determined by its temperature. When a certain temperature threshold unique to each substance in the universe is crossed, a phase change will result, changing the state of the matter. Under conditions of constant pressure temperature is the primary determinant of a substance's phase. The differential in temperatures and the phases of different kinds of matter allows for the operation of heat engines and refrigerators.

TL;DR (Too Long; Didn't Read)

Temperature has a direct effect on whether a substance exists as a solid, liquid or gas. Generally, increasing the temperature turns solids into liquids and liquids into gases; reducing it turns gases into liquids and liquids into solids.

At low temperatures, molecular motion decreases and substances have less internal energy. Atoms will settle into low energy states relative to one another and move very little, which is characteristic of solid matter. As temperatures increase, additional heat energy is applied to the constituent parts of a solid, which causes additional molecular motion. Molecules begin to push against one another and the overall volume of a substance increases. At this point, the matter has entered the liquid state. A gaseous state exists when molecules have absorbed so much heat energy due to increased temperatures that they are free to move around one another at high speeds.

The point at which matter subjected to a particular temperature under conditions of constant pressure begins to change its phase is called the phase change threshold. At this temperature, every bit of the substance exposed to the heat will change its state. A shift from to a solid to a liquid occurs at the melting point, and the transition from a liquid to a gas takes place at the boiling point. Conversely, the moment of change from a gas to a liquid is the condensation point and the shift from a liquid to a solid takes place at the freezing point.

A substance may undergo phase change from a solid to a gas or from a gas to a solid if the temperature it is exposed to is changed very quickly. If the temperature around a solid is raised very quickly, it can sublimate, or phase change from a solid to a gas without existing as a liquid. In the opposite direction, a gas that is suddenly supercooled can undergo complete deposition.

If pressure is constant, the state of a substance will depend entirely on the temperature it is exposed to. For this reason, ice melts if taken out of a freezer and water boils out of a pot if left at too high a temperature for too long. Temperature is merely a measurement of the amount of heat energy present in the surroundings. When a substance is placed in surroundings of a different temperature, heat is exchanged between the substance and the surroundings, causing both to achieve an equilibrium temperature. So when an ice cube is exposed to heat, its water molecules absorb heat energy from the surrounding atmosphere and begin to move more energetically, causing the water ice to melt into liquid water.

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What Is the Effect of Temperature on States of Matter?

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Matter can exist in a solid, liquid or gaseous state, and the state a substance is in can be largely determined by its temperature. When a certain temperature threshold unique to each substance in the universe is crossed, a phase change will result, changing the state of the matter.

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The temperature change while changing different aspects of a substance such  as mass  type of matter because the object is determined by it's temperature.

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Matter can exist in a solid, liquid or gaseous state, and the state a substance is in can be largely determined by its temperature. When a certain temperature threshold unique to each substance in the universe is crossed, a phase change will result, changing the state of the matter. Under conditions of constant pressure temperature is the primary determinant of a substance's phase. The differential in temperatures and the phases of different kinds of matter allows for the operation of heat engines and refrigerators.

TL;DR (Too Long; Didn't Read)

Temperature has a direct effect on whether a substance exists as a solid, liquid or gas. Generally, increasing the temperature turns solids into liquids and liquids into gases; reducing it turns gases into liquids and liquids into solids.

At low temperatures, molecular motion decreases and substances have less internal energy. Atoms will settle into low energy states relative to one another and move very little, which is characteristic of solid matter. As temperatures increase, additional heat energy is applied to the constituent parts of a solid, which causes additional molecular motion. Molecules begin to push against one another and the overall volume of a substance increases. At this point, the matter has entered the liquid state. A gaseous state exists when molecules have absorbed so much heat energy due to increased temperatures that they are free to move around one another at high speeds.

The point at which matter subjected to a particular temperature under conditions of constant pressure begins to change its phase is called the phase change threshold. At this temperature, every bit of the substance exposed to the heat will change its state. A shift from to a solid to a liquid occurs at the melting point, and the transition from a liquid to a gas takes place at the boiling point. Conversely, the moment of change from a gas to a liquid is the condensation point and the shift from a liquid to a solid takes place at the freezing point.

A substance may undergo phase change from a solid to a gas or from a gas to a solid if the temperature it is exposed to is changed very quickly. If the temperature around a solid is raised very quickly, it can sublimate, or phase change from a solid to a gas without existing as a liquid. In the opposite direction, a gas that is suddenly supercooled can undergo complete deposition.

If pressure is constant, the state of a substance will depend entirely on the temperature it is exposed to. For this reason, ice melts if taken out of a freezer and water boils out of a pot if left at too high a temperature for too long. Temperature is merely a measurement of the amount of heat energy present in the surroundings. When a substance is placed in surroundings of a different temperature, heat is exchanged between the substance and the surroundings, causing both to achieve an equilibrium temperature. So when an ice cube is exposed to heat, its water molecules absorb heat energy from the surrounding atmosphere and begin to move more energetically, causing the water ice to melt into liquid water.

# data[].attributes.attachment_link.title
What Is the Effect of Temperature on States of Matter?

# data[].attributes.attachment_link.description
Matter can exist in a solid, liquid or gaseous state, and the state a substance is in can be largely determined by its temperature. When a certain temperature threshold unique to each substance in the universe is crossed, a phase change will result, changing the state of the matter.

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jailee video

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Changes of State | Matter |  Physics | FuseSchool

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The difference between a physical reaction and a chemical reaction is composition. In a chemical reaction, there is a change in the composition of the substances in question; in a physical change.

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When heat is added to a substance the molecules and atoms vibrate faster. As atoms vibrate faster the space between atoms increases

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Learning Objectives

By the end of this section, you will be able to:

Observe heat transfer and change in temperature and mass.

Calculate final temperature after heat transfer between two objects.

One of the major effects of heat transfer is temperature change: heating increases the temperature while cooling decreases it. We assume that there is no phase change and that no work is done on or by the system. Experiments show that the transferred heat depends on three factors-the change in temperature, the mass of the system, and the substance and phase of the substance.

The dependence on temperature change and mass are easily understood. Owing to the fact that the (average) kinetic energy of an atom or molecule is proportional to the absolute temperature, the internal energy of a system is proportional to the absolute temperature and the number of atoms or molecules. Owing to the fact that the transferred heat is equal to the change in the internal energy, the heat is proportional to the mass of the substance and the temperature change. The transferred heat also depends on the substance so that, for example, the heat necessary to raise the temperature is less for alcohol than for water. For the same substance, the transferred heat also depends on the phase (gas, liquid, or solid).

Heat Transfer and Temperature Change

The quantitative relationship between heat transfer and temperature change contains all three factors: Q = mcΔ T, where Q is the symbol for heat transfer, m is the mass of the substance, and Δ T is the change in temperature. The symbol c stands for specific heat and depends on the material and phase. The specific heat is the amount of heat necessary to change the temperature of 1.00 kg of mass by 1.00ºC. The specific heat c is a property of the substance; its SI unit is J/(kg ⋅ K) or J/(kg ⋅ ºC). Recall that the temperature change (Δ T) is the same in units of kelvin and degrees Celsius. If heat transfer is measured in kilocalories, then the unit of specific heat is kcal/(kg ⋅ ºC).

Values of specific heat must generally be looked up in tables, because there is no simple way to calculate them. In general, the specific heat also depends on the temperature. Table 1 lists representative values of specific heat for various substances. Except for gases, the temperature and volume dependence of the specific heat of most substances is weak. We see from this table that the specific heat of water is five times that of glass and ten times that of iron, which means that it takes five times as much heat to raise the temperature of water the same amount as for glass and ten times as much heat to raise the temperature of water as for iron. In fact, water has one of the largest specific heats of any material, which is important for sustaining life on Earth.

Example 1. Calculating the Required Heat: Heating Water in an Aluminum Pan

A 0.500 kg aluminum pan on a stove is used to heat 0.250 liters of water from 20.0ºC to 80.0ºC. (a) How much heat is required? What percentage of the heat is used to raise the temperature of (b) the pan and (c) the water?

Strategy

The pan and the water are always at the same temperature. When you put the pan on the stove, the temperature of the water and the pan is increased by the same amount. We use the equation for the heat transfer for the given temperature change and mass of water and aluminum. The specific heat values for water and aluminum are given in Table 1.

Solution

Because water is in thermal contact with the aluminum, the pan and the water are at the same temperature.

Calculate the temperature difference:

Calculate the mass of water. Because the density of water is 1000 kg/m ³, one liter of water has a mass of 1 kg, and the mass of 0.250 liters of water is m = 0.250 kg.

Calculate the heat transferred to the water. Use the specific heat of water in Table 1:

Calculate the heat transferred to the aluminum. Use the specific heat for aluminum in Table 1:

Compare the percentage of heat going into the pan versus that going into the water. First, find the total transferred heat:

Thus, the amount of heat going into heating the pan is

[latex]\frac{27.0\text{ kJ}}{89.8\text{ kJ}}\times100\%=30.1\%\\[/latex]

and the amount going into heating the water is

[latex]\frac{62.8\text{ kJ}}{89.8\text{ kJ}}\times100\%=69.9\%\\[/latex].

Discussion

In this example, the heat transferred to the container is a significant fraction of the total transferred heat. Although the mass of the pan is twice that of the water, the specific heat of water is over four times greater than that of aluminum. Therefore, it takes a bit more than twice the heat to achieve the given temperature change for the water as compared to the aluminum pan.

Example 2. Calculating the Temperature Increase from the Work Done on a Substance: Truck Brakes Overheat on Downhill Runs

Truck brakes used to control speed on a downhill run do work, converting gravitational potential energy into increased internal energy (higher temperature) of the brake material. This conversion prevents the gravitational potential energy from being converted into kinetic energy of the truck. The problem is that the mass of the truck is large compared with that of the brake material absorbing the energy, and the temperature increase may occur too fast for sufficient heat to transfer from the brakes to the environment.

Calculate the temperature increase of 100 kg of brake material with an average specific heat of 800 J/kg ⋅ ºC if the material retains 10% of the energy from a 10,000-kg truck descending 75.0 m (in vertical displacement) at a constant speed.

Strategy

If the brakes are not applied, gravitational potential energy is converted into kinetic energy. When brakes are applied, gravitational potential energy is converted into internal energy of the brake material. We first calculate the gravitational potential energy ( Mgh) that the entire truck loses in its descent and then find the temperature increase produced in the brake material alone.

Solution

1. Calculate the change in gravitational potential energy as the truck goes downhill Mgh = (10,000 kg)(9.80 m/s²)(75.0 m) = 7.35 × 10⁶ J.

2. Calculate the temperature from the heat transferred using Q = Mgh and [latex]\Delta{T}=\frac{Q}{mc}\\[/latex], where m is the mass of the brake material. Insert the values m = 100 kg and c = 800 J/kg ⋅ ºC to find [latex]\Delta{T}=\frac{\left(7.35\times10^6\text{ J}\right)}{\left(100\text{ kg}\right)\left(800\text{ J/kg}^{\circ}\text{C}\right)}=92^{\circ}C\\[/latex].

Discussion

This temperature is close to the boiling point of water. If the truck had been traveling for some time, then just before the descent, the brake temperature would likely be higher than the ambient temperature. The temperature increase in the descent would likely raise the temperature of the brake material above the boiling point of water, so this technique is not practical. However, the same idea underlies the recent hybrid technology of cars, where mechanical energy (gravitational potential energy) is converted by the brakes into electrical energy (battery).

Note that Example 2 is an illustration of the mechanical equivalent of heat. Alternatively, the temperature increase could be produced by a blow torch instead of mechanically.

Example 3. Calculating the Final Temperature When Heat Is Transferred Between Two Bodies: Pouring Cold Water in a Hot Pan

Suppose you pour 0.250 kg of 20.0ºC water (about a cup) into a 0.500-kg aluminum pan off the stove with a temperature of 150ºC. Assume that the pan is placed on an insulated pad and that a negligible amount of water boils off. What is the temperature when the water and pan reach thermal equilibrium a short time later?

Strategy

The pan is placed on an insulated pad so that little heat transfer occurs with the surroundings. Originally the pan and water are not in thermal equilibrium: the pan is at a higher temperature than the water. Heat transfer then restores thermal equilibrium once the water and pan are in contact. Because heat transfer between the pan and water takes place rapidly, the mass of evaporated water is negligible and the magnitude of the heat lost by the pan is equal to the heat gained by the water. The exchange of heat stops once a thermal equilibrium between the pan and the water is achieved. The heat exchange can be written as | Q hot|= Q cold.

Solution

Use the equation for heat transfer Q = mcΔ T to express the heat lost by the aluminum pan in terms of the mass of the pan, the specific heat of aluminum, the initial temperature of the pan, and the final temperature: Q hot = m Al c Al( T f − 150ºC).

Express the heat gained by the water in terms of the mass of the water, the specific heat of water, the initial temperature of the water and the final temperature: Q cold = m W c W( T f − 20.0ºC).

Note that Q hot<0 and Q cold>0 and that they must sum to zero because the heat lost by the hot pan must be the same as the heat gained by the cold water:

[latex]\begin{array}{lll}Q_{\text{cold}}+Q_{\text{hot}}&=&0\\Q_{\text{cold}}&=&-Q_{\text{hot}}\\m_{\text{W}}c_{\text{W}}\left(T_{\text{f}}-20.0^{\circ}\text{C}\right)&=&-m_{\text{Al}}c_{\text{Al}}\left(T_{\text{f}}-150^{\circ}\text{C}\right)\end{array}\\[/latex]

This an equation for the unknown final temperature, T f.

Bring all terms involving T f on the left hand side and all other terms on the right hand side. Solve for T f,

[latex]\displaystyle{T_{\text{f}}}=\frac{m_{\text{Al}}c_{\text{Al}}\left(T_{\text{f}}-150^{\circ}\text{C}\right)+m_{\text{W}}c_{\text{W}}\left(T_{\text{f}}-20.0^{\circ}\text{C}\right)}{m_{\text{Al}}c_{\text{Al}}+m_{\text{W}}c_{\text{W}}}\\[/latex],

and insert the numerical values:

[latex]\begin{array}{lll}T_{\text{f}}&=&\frac{\left(0.500\text{ kg}\right)\left(900\text{ J/kg}^{\circ}\text{C}\right)\left(150^{\circ}\text{C}\right)+\left(0.250\text{ kg}\right)\left(4186\text{ J/kg}^{\circ}\text{C}\right)\left(20.0^{\circ}\text{C}\right)}{\left(0.500\text{ kg}\right)\left(900\text{ J/kg}^{\circ}\text{C}\right)+\left(0.250\text{ kg}\right)\left(4186\text{ J/kg}^{\circ}\text{C}\right)}\\\text{ }&=&\frac{88430\text{ J}}{1496.5\text{ J}/^{\circ}\text{C}}\\\text{ }&=&59.1^{\circ}\text{C}\end{array}\\[/latex]
Discussion
This is a typical calorimetry problem-two bodies at different temperatures are brought in contact with each other and exchange heat until a common temperature is reached. Why is the final temperature so much closer to 20.0ºC than 150ºC? The reason is that water has a greater specific heat than most common substances and thus undergoes a small temperature change for a given heat transfer. A large body of water, such as a lake, requires a large amount of heat to increase its temperature appreciably. This explains why the temperature of a lake stays relatively constant during a day even when the temperature change of the air is large. However, the water temperature does change over longer times (e.g., summer to winter).

Take-Home Experiment: Temperature Change of Land and Water

What heats faster, land or water?

To study differences in heat capacity:

Place equal masses of dry sand (or soil) and water at the same temperature into two small jars. (The average density of soil or sand is about 1.6 times that of water, so you can achieve approximately equal masses by using 50% more water by volume.)

Heat both (using an oven or a heat lamp) for the same amount of time.

Record the final temperature of the two masses.

Now bring both jars to the same temperature by heating for a longer period of time.

Remove the jars from the heat source and measure their temperature every 5 minutes for about 30 minutes.

Which sample cools off the fastest? This activity replicates the phenomena responsible for land breezes and sea breezes.

Check Your Understanding

If 25 kJ is necessary to raise the temperature of a block from 25ºC to 30ºC, how much heat is necessary to heat the block from 45ºC to 50ºC?

Solution

The heat transfer depends only on the temperature difference. Since the temperature differences are the same in both cases, the same 25 kJ is necessary in the second case.

Section Summary

The transfer of heat Q that leads to a change ΔT in the temperature of a body with mass m is Q = mcΔT, where c is the specific heat of the material. This relationship can also be considered as the definition of specific heat.

Conceptual Questions

1. What three factors affect the heat transfer that is necessary to change an object's temperature?

2. The brakes in a car increase in temperature by ΔT when bringing the car to rest from a speed v. How much greater would ΔT be if the car initially had twice the speed? You may assume the car to stop sufficiently fast so that no heat transfers out of the brakes.

Problems & Exercises

1. On a hot day, the temperature of an 80,000-L swimming pool increases by 1.50ºC. What is the net heat transfer during this heating? Ignore any complications, such as loss of water by evaporation.

2. Show that 1 cal/g · ºC =1 kcal/kg · ºC.

3. To sterilize a 50.0-g glass baby bottle, we must raise its temperature from 22.0ºC to 95.0ºC. How much heat transfer is required?

4. The same heat transfer into identical masses of different substances produces different temperature changes. Calculate the final temperature when 1.00 kcal of heat transfers into 1.00 kg of the following, originally at 20.0ºC: (a) water; (b) concrete; (c) steel; and (d) mercury.

5. Rubbing your hands together warms them by converting work into thermal energy. If a woman rubs her hands back and forth for a total of 20 rubs, at a distance of 7.50 cm per rub, and with an average frictional force of 40.0 N, what is the temperature increase? The mass of tissues warmed is only 0.100 kg, mostly in the palms and fingers.

6. A 0.250-kg block of a pure material is heated from 20.0ºC to 65.0ºC by the addition of 4.35 kJ of energy. Calculate its specific heat and identify the substance of which it is most likely composed.

7. Suppose identical amounts of heat transfer into different masses of copper and water, causing identical changes in temperature. What is the ratio of the mass of copper to water?

8. (a) The number of kilocalories in food is determined by calorimetry techniques in which the food is burned and the amount of heat transfer is measured. How many kilocalories per gram are there in a 5.00-g peanut if the energy from burning it is transferred to 0.500 kg of water held in a 0.100-kg aluminum cup, causing a 54.9ºC temperature increase? (b) Compare your answer to labeling information found on a package of peanuts and comment on whether the values are consistent.

9. Following vigorous exercise, the body temperature of an 80.0-kg person is 40.0ºC. At what rate in watts must the person transfer thermal energy to reduce the the body temperature to 37.0ºC in 30.0 min, assuming the body continues to produce energy at the rate of 150 W? 1 watt = 1 joule/second or 1 W = 1 J/s.

10. Even when shut down after a period of normal use, a large commercial nuclear reactor transfers thermal energy at the rate of 150 MW by the radioactive decay of fission products. This heat transfer causes a rapid increase in temperature if the cooling system fails (1 watt = 1 joule/second or 1 W = 1 J/s and 1 MW = 1 megawatt). (a) Calculate the rate of temperature increase in degrees Celsius per second (ºC/s) if the mass of the reactor core is 1.60 × 10⁵ kg and it has an average specific heat of 0.3349 kJ/kg ⋅ ºC. (b) How long would it take to obtain a temperature increase of 2000ºC, which could cause some metals holding the radioactive materials to melt? (The initial rate of temperature increase would be greater than that calculated here because the heat transfer is concentrated in a smaller mass. Later, however, the temperature increase would slow down because the 5 × 10⁵-kg steel containment vessel would also begin to heat up.)

Glossary

specific heat: the amount of heat necessary to change the temperature of 1.00 kg of a substance by 1.00 ºC

Selected Solutions to Problems & Exercises

1. 5.02 × 10 ⁸ J

3. 3.07 × 10 ³ J

5. 0.171ºC

7. 10.8

9. 617 W

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By the end of this section, you will be able to: Observe heat transfer and change in temperature and mass. Calculate final temperature after heat transfer between two objects. One of the major effects of heat transfer is temperature change: heating increases the temperature while cooling decreases it.

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Adding heat makes the particle motion have energy and act fast but when you remove heat it makes the particles motion slower.