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what is acid rain ?

> it is a broad term that includes any form of precipitation with acidic components such as :
- sulfuric
- nitric acid
that falls to the ground from the atmosphere in wet or dry forms .
This can include : rain
- snow
- fog
- hail
or even dust that is acidic

what causes acid rain ?

> it is resulted when sulfur dioxide ( SO2 ) & nitrogen oxide (NOx) are being emitted into the atmosphere & being transported by wind .
> the sulfur dioxide & the nitrogen oxide reacts with water , oxygen , & other chemicals to form sulfuric & nitric acids & is mix with water & other materials before falling to earth
> with the small portion of sulfur oxide & nitrogen oxide , the cause of acid rain is natural resources such as :
- volcanoes

mostly coming from the burning of fossil fuels
what are the effects of acid rain :

the effects on fish & wildlife

> as the acid rain flows through the soil , the acidic rain water can leach aluminium from soil clay particles & then flow into river & streams

the effects on plants

> acid rain removes minerals & nutrients
> the acidic fogs & clouds might also strip nutrients from tree foliage

the effects on materials

> damage surfaces
> corrode metal
> cause paint & stone to deteriorate quickly
> they also dirty materials

the effects on human

> SO2 & NOx both forms fine sulfate & nitrate particles that we inhale
Studies has shown that inhaling these particles can cause heart & lung disorders such as :
- asthma
- bronchitis

# data[].attributes.body
What is Acid Rain?
- Acid rain is any form of precipitation with acidic components such as sulfuric or nitric acid that falls to the ground from the atmosphere in wet or dry forms

What causes acid rain?
- When sulfur dioxide and nitrogen oxides are emitted into the atmosphere and transported by wind and air currents, it will cause acid rain

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WHAT IS ACID RAIN AND WHAT CAUSES IT?
rainfall made so acidic by atmospheric pollution that it causes environmental harm, to forests and lakes. The main cause is the industrial burning of coal and other fossil fuels, the waste gases which contain sulphur and nitrogen oxides which combine with atmospheric water to form acids.

EFFECTS OF ACID RAIN
-acidic rain water can leach aluminum from soil clay particles and then flow into streams and lakes. The more acid that is introduced to the ecosystem, the more aluminum is released.

-Acid rain leaches aluminum from the soil.  That aluminum may be harmful to plants as well as animals. Acid rain also removes minerals and nutrients from the soil that trees need to grow.

At high elevations, acidic fog and clouds might strip nutrients from trees’ foliage, leaving them with brown or dead leaves and needles. The trees are then less able to absorb sunlight, which makes them weak and less able to withstand freezing temperatures.

-Acid rain also contains nitrogen, and this can have an impact on some ecosystems. For example, nitrogen pollution in our coastal waters is partially responsible for declining fish and shellfish populations in some areas. In addition to agriculture and wastewater, much of the nitrogen produced by human activity that reaches coastal waters comes from the atmosphere.

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1. What is Acid Rain?

Acid rain is a result of air pollution. When any type of fuel is burnt, lots of different chemicals are produced. The smoke that comes from a fire or the fumes that come out of a car exhaust don't just contain the sooty grey particles that you can see - they also contains lots of invisible gases that can be even more harmful to our environment.

Power stations, factories and cars all burn fuels and therefore they all produce polluting gases. Some of these gases (especially nitrogen oxides and sulfur dioxide) react with the tiny droplets of water in clouds to form sulphuric and nitric acids. The rain from these clouds then falls as very weak acid - which is why it is known as "acid rain".

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What is acid rain?
Acid rain, or acid deposition, is a broad term that includes any form of precipitation with acidic components, such as sulphuric or nitric acid that fall to the ground from the atmosphere in wet or dry forms.  This can include rain, snow, fog, hail or even dust that is acidic.
What causes acid rain?
Acid rain results when sulfur dioxide (SO2) and nitrogen oxides (NOX) are emitted into the atmosphere and transported by wind and air currents.  The SO2 and NOX react with water, oxygen and other chemicals to form sulfuric and nitric acids.  These then mix with water and other materials before falling to the ground.
Harmful effect of acid rain:
- kill plants
- kill fishes
- damage buildings and statues
Chemical equation of acid rain:
Sulfur + oxygen --> sulfur dioxide (gas) + water (h2O)
Sulfer Dioxide + Water --> sulfuric acid

# data[].attributes.body
rainfall made so acidic by atmospheric pollution that it causes environmental harm.The main cause is the industrial burning of coal and other fossil fuels, the waste gases from which contain sulphur and nitrogen oxides which combine with atmospheric water to form acids
Taj was here
:)

# data[].attributes.body
What is Acid Rain?
✳ Rainfall made so acidic by atmospheric pollution that it causes environmental harm, chiefly to forests and lakes. The main cause is the industrial burning of coal and other fossil fuels, the waste gases from which contain sulfur and nitrogen oxides which combine with atmospheric water to form acids.
Effects of acid rain
✳ Acid rain makes waters acidic and causes them to absorb the aluminum that makes its water from soil into lakes and streams.
What is the cause of acid rain?
✳Acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air.
Harmful effects:
↪ Animals living in the sea will die
↪ Trees will die
↪ Damage to human health (Walking in acid rain, or even swimming in an acid lake, is no more dangerous than walking or swimming in clean water. )

# data[].attributes.body
What is Acid Rain?
--> Acid rain is certain gases mixed with atmospheric moisture to create precipitation that is more acidic than normal.

How is Acid Rain formed?
--> Sulfur dioxide and nitrogen oxides are two of the gases involved in the creation of acid rain.
--> When these gases are being released into the environment and mixed with water, oxygen, and other chemicals, it creates acidic compounds resulting in the formation of acid rain.

What are the effects of Acid Rain?
--> Acid rain can negatively affect human health by creating particles in the air that cause respiratory problems.
--> Acid rain does not kill trees directly but seeps into the soil and dissolves many of the essential nutrients the trees need.Trees become more susceptible to infection, insects, and are less resistant to cold weather.

What is the word equation for Acid Rain?
Sulfer Dioxide + Water --> Sulfer Acid
Nitrogen Oxide + Water --> Nitric Acid

# data[].attributes.body
what is acid rain?
: acid rain is an acidic rainfall that is by atmospheric pollution which causes environmental harm.

how is acid rain formed?
acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air. the substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain.

the effects of acid rain?
the effects of acid rain is that it makes waters acidic and causes them to absorb the aluminium that makes its way from soil into lakes, which can cause harm to the ecological environment.

what is the word equation for acid rain?
sulfur dioxide + water -> sulfer acid
nitrogen oxide + water -> nitrate acid

# data[].attributes.body
How is acid rain formed?
>Acid rain is a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air.

What is acid rain?
>It is rainfall made so acidic by atmospheric pollution that it causes environmental harm, chiefly to forests and lakes.

What is the word equation for Acid Rain?
>Sulfer Dioxide + Water --> Sulfer Acid
>Nitrogen Oxide + water -> Nitrate Acid

Harmful effect on acid rain
> Increase in dead plants and trees
> Corrosion of buildings
> Exposure to acid rain will cause skin problems

# data[].attributes.body
What is acid rain?: Acid rain is rain that has become acidic by pollutants. It is a type of acid deposition. Acid deposition falls on buildings,trees and can make lakes acidic.

Causes of acid rain:
- harmful pollutants in the air. It may mix with water, oxygen and chemicals and become acidic pollutants

- human activities
power plants release nitrogen oxide and sulfur dioxide when they burn fossil fuels to produce electricity, exhaust from vehicles release nitrogen oxide and sulfur dioxide into the atmosphere.

Effects of acid rain:
- health problems
Acid rain may cause respiratory diseases(asthma or chronic bronchitis) or make it worse when humans breathe in the tiny particles caused by acid rain.

-Harms forests
Acid rain that seeps into the ground can dissolve nutrients like magnesium and calcium that is needed by trees to be healthy. It also causes aluminium to be released into the soil and makes it difficult for trees to absorb water.

-damages lakes and streams
The pH level of the water gets lower(acidic) which is deadly to marine animals and water plants.

-damages buildings and objects
The chemicals found in acid rain can cause paint to peel and stone statues to appear old and worn down, which reduces their value and beauty.

What is the word equation?
Sulfur dioxide + water---> sulfuric acid
Nitrogen oxide + water----> nitric acid

# data[].attributes.body
What is Acid Rain ?

It is a rainfall that is acidic and it is made by atmospheric pollution that causes environmental harm especially to forests and lakes.

The main cause is the industrial burning of coal and other fossil fuels, the waste gases from which contain sulphur and nitrogen oxides which combine with atmospheric water to form acids.

Cause of Acid Rain

Acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air.

[WRITE THE WORD EQUATION ON HOW ACID RAIN IS FORMED?]

These substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants.

Effects of Acid Rain

Acid rain has many ecological effects, but none is greater than its impact on lakes, streams, wetlands, and other aquatic environments.

Acid rain makes waters acidic and causes them to absorb the aluminium that makes its way from soil into lakes and streams.

Word equation

Sulfer+Oxygen->Sulfer dioxide

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Name: Janani

Acid rain is caused by a chemical reaction.  When compounds like sulfur dioxide and nitrogen oxides are released into the air, They mix with other substances like water and oxygen, and can rise very high into the atmosphere, where they mix and react with water, oxygen,to form more acidic pollutants, and eventually falling as  acid rain.

Acid rain can also be caused by the burning of fossil fuels

[WRITE THE WORD EQUATION OF HOW ACID RAIN IS FORMED?]

Acid rain makes water bodies more acidic. This lowers the pH value which kills many aquatic animals and plants. It also lowers pH of the soil, and robs away its nutrients, causing improper growth of plants

Acid rain can cause degradation of man made architectures

sulfur dioxide + water  -------------> sulfuric acid
nitrogen oxide + water --------------> Nitric acid

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Members: Xian Yang(LEADER),Dean, Syed,Mashuo, Rachel Ong, Fariah,Hillman
At the molecular level, chemical change involves making or breaking of bonds between atoms. These changes are chemical: iron rusting (iron oxide forms)gasoline burning (water vapor and carbon dioxide form)

Benefits:-Nature(e.g decayad respiration)
-Farming
-Manufacturing
-cooking
-Healthcare
Harm:-Rusting
-Burning
-Decay of food
Indicators:Acids-Turn Blue litmus red
-pH
Alkalis- Turn red litmus blue
- pH>7
Neutral solutions- No change with litmus
-pH=7
Characteristics:- Produce new substances
- Involve absorption or release of energy
-Matter/mass is always conserved
Heat:-Thermal decomposition
-Combustion
-oxidation
Light:-Photosynthesis
-Photography
Electricity:-Electrolysis(e.g electroplating)
Mixing substances:- Acids+metals--->Salt+hydrogen
-Acids+carbonates---->salt+carbon dioxide+ water
-Acids +alkalis--->salt+ water(neutralisation)

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Members: Jun Kai ,  Kadrian , Tanya , Nisrina
Chemical Change :
- A physical change is a change in which no new substance is formed.
- A chemical change is a change in which a new substance is formed
How do we represent chemical reactions?
- represent using word equations
. shows reactants
. shows the products
. shows the conditions in a chemical reaction
Electrolysis:
- The use of electricity to cause a chemical change is called electrolysis.
Chemical Change:
Thermal Decomposition
- a single substance breaks up into two or more simpler
Combustion
-a substance reacts with oxygen when heated to form one or more new substances.
Oxidation
-The addition of oxygen to a substance is called oxidation.
-Oxidation reactions also occur when other elements , metals and non- metals, burn in air.

magnesium + oxygen --> magnesium oxide

Respiration
-Respiration takes place in every cell in an organism
GLUCOSE+OXYGEN ---------> CARBON DIOXIDE+WATER+ENERGY
(in living cells)
What happens when matter and light interact?

PHOTOSYNTHESIS:
It is a process in which green plants use light energy to make food.
CARBON DIOXIDE+WATER-----> GLUCOSE+ENERGY.

PHOTOGRAPHY:
The greater the exposure to light, the darker the area of the film
SILVER BROMIDE ------> SILVER ( grey solid ) + BROMINE

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Members: Taj ,Francis,Norven,Yong Kiat ,Juani
•Physical changes:A physical change is a change in which no new substance is formed
•Chemical changes:A chemical change is a change is formed
•The substance that react to each other is called reactants,the new substance form is called product. Sometimes a factor is needed to let the reactants to
•Combustion: a substance reacts with oxygen when heated to form one or more substances.

Example: carbon + oxygen =carbon dioxide+ heat

Thermal decomposition = a single substance break up into two or more simpler substance when it is heated.
Example: Sugar + heat = carbon+ water vapour

•Respiration takes place in every cell in an organism that involves
Example: glucose + oxygen= carbon dioxide+ water + energy
o xidation and combine with food,such as glucose to release energy.
•Oxidation is the addtion to a substance is called oxidation
During the reaction,carbon dioxide and water are produced.•
Example: iron+oxygen= iron oxide (rust)
•Ph value classified as acidic and alkaline with acidic having Ph value of less than 7 and alkaline have PH value more than 7 while Ph value of 7 is neither acidic or alkaline.

Measuring Ph value using a litmus and universal indicator .
Substance that is very alkaline and acidic are very corrosive and can burn your skin.

Mixed Substances:
Acids and metals : hydrochloric acid + magnesium ----> magnesium chloride + hydrogen gas.
Acids and carbonates : acid + carbonate ---> salt + carbon dioxide gas + water.
Acids and alkalis : hydrochloric + sodium hydroxide ---> sodium chloride + water
Photosynthesis is the process in which green plant use light energy to make food:carbon dioxide + water =glucose + oxygen.
Photography: The coating on black and white photographic film contain silver bromide .Exposure to light decomposes the silver bromide into silver which produces the dark areas on the film:silver bromide=silver +  bromide.
The use of electricity to cause a chemical change is called electrolysis.This is the chemical effect of a current.Electrolysis is used in the process of electroplating ,the process of coating an object with a thin layer of a metal: copper chlorine = copper + chlorine

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Members : rabbit,ang mo,baby bop,giraffe,rgee-anne,pinkie
(rachel chng,ashley,karinia,manyi,ryan,donovan)
CHANGES:
-physical [ a physical change is a change in which no new substance is formed ] * physical change can be reversed*
-chemical [ a chemical change is a change in which a new substance is formed ]
- physical change : change of state (liquid to gas)
- chemical change : also called chemical reactions, eg. rusting
- in chemical reaction, substances (reactants) react with each other to form new substances (called products).
Eg. iron is a reactant and rust is a product.
- we write word equations to show what happens in chemical reactions, they show the reactants, products and sometimes the conditions
[ changes occur because of interactions, interactions may be between matter and energy, such as heat,light or electricity ]

THERMAL DECOMPOSITION:
- a single substance breaks up into 2 or more substances when it is heated
Eg. sugar --HEAT--> carbon + water vapour

COMBUSTION:
-A substance reacting with oxygen when heated to form one or more substances.
-Heat and/or light will be given out
ie. carbon+oxygen --------> Carbon dioxide + heat
Combustion reactions are very common. Burning of fuels such as coal, natural gas and petrol are egs.

OXIDATION:
- the addition of oxygen to a substance is called oxidation.
- oxidation reactions also occur when other elements, metals and non metals burn in the air.
Eg. magnesium burns in air, new substance magnesium oxide is formed.
magnesium + oxygen --------> magnesium oxide
- this reaction is both a combustion reaction (bc magnesium burns in air) and an oxidation (bc oxygen is added to the magnesium)

Respiration:
- an eg of a process that involves oxidation
- it takes place in every cell in an organism in the cell, food such as glucose combines with oxygen and releases energy.
- during the reaction, carbon dioxide and water are produced
glucose + oxygen ---in living cells--> carbon dioxide+water+energy

Light is also involved in physical and chemical changes. Light sometimes causes the changes, in other changes, light is given out.

Electricity is also involved in chemical reactions .
~ Electrolysis
- use of electricity to cause a chemical change is also the chemical effect of a current.
- it is used in the process of electroplating , coating of an object with a thin layer of metal.
copper chloride -- electricity--> copper + chlorine

Chemical changes may also occur when substances are mixed together.
Acids and Metals :
when dilute acids are mixed with certain metals, hydrogen gas and a salt are produced.
hydrochloric acid + magnesium ---> magnesium chloride + hydrogen gas
* magnesium chloride is an example of a substance (salt)
* reaction of any dilute acid with most metals :
acid + metal ---> salt + hydrogen gas
Acids and carbonates:
dilute hydrochloric acid is added to chalk (solid calcium carbonate), carbon dioxide gas, a salt and water are produced.
* hydrochloric acid + calcium carbonate ---> calcium chloride + carbon dioxide gas + water
Calcium chloride is another salt :
* acid + carbonate --> salt + carbon dioxide gas + water
Acids and alkalis - neutralisation
- bacteria in your mouth change sugary food into acid that attacks the teeth and cause tooth decay.
Toothpaste contains weak alkalis. When mixed with acids, a chemical reaction called neutralisation occurs. During the process, properties of the acid and the alkali are ' neutralised', preventing tooth decay.
* sodium chloride :
acid + alkali --> salt + water

Acids, alkalis and indicators :
- to tell if a solution is alkali or acid, use an indicator.
Indicators are substances that show one colour in acids and another in alkalis.
1. Litmus indicator (either red or blue)
It is a dye obtained from lichens (a plant like organism). Litmus is used as a solution or in paper form.
If it turns red, the liquid is acidic. If it turns blue, its alkaline.
2. other natural indicators
brightly coloured flowers, vegetables or berries are good indicators.
Eg, coloured juice extracted from red cabbage is pink in acids and green in alkaline.
Another interesting indicator is the hydrangea flower, flowers are different colours when grown in acidic or alkaline soil.
3. Universal indicator
A mixture of other indicators, used in the form of solution or paper.
The indicator changes colour when its added into different substances.
Each colour corresponds to a pH scale.
4. pH meter
to get accurate values. The electrode is dipped into a solution and the pH value of the solution will be read from the meter.

pH values:
tells us how acidic or alkaline a substance is.
Acids: pH value less than 7 ( low pH, more acidic)(higher pH, less acidic)
Alkalis: pH value greater than 7 (high pH, more alkaline)(low pH, less alkaline)
Neutral: pH value of 7
* more acidic or more alkaline, more dangerous. They are corrosive and can burn your skin. less acidic, less alkaline, they are not corrosive, safe to eat.
What happens to matter in chemical change?
number of atoms of reactants = number of atoms of products
* atoms are not created or destroyed, only rearranged.
mass of reactants = mass of products
* mass of matter is not increased or decreased, the mass is conserved(unchanged).

[ benefits / harmful effects of chemical reactions ]
benefits:                              harmful:
- in nature  - burning (air pollutant; lung disease,acid rain)
- in farming  - rusting
- in manufacturing  - decay of food
- in hygiene
- in cooking
- in healthcare

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Members: Qian Yu, Brenna, Chloe, Ellen 2C

PHYSICAL CHANGES do not involve a change in a identity or chemical makeup  of that substances.

Example of physical changes: Water evaporates from the surface of the ocean.

All physical changes are not necessarily accompanied by a chemical change.

CHEMICAL CHANGES  involve a change in a identity or chemical makeup  of that substances.

Example of chemical changes:Rust forms on a nail left outside.

CHEMICAL CHANGES  is change that results in the formation of new chemical substances. At the molecular level, chemical change involves making or breaking of bonds between atoms.

Physical changes occur when objects or substances undergo a change that does not change their chemical composition.

A physical change is any change NOT involving a change in the substance's chemical identity.

iron (and other metals) can be made to be magnetic. This change in no way affects the chemical identity of the element. Iron that is magnetized rusts just as easily as iron that is not magnetized. (Yes, rusting is a chemical change. Rust is chemically different from iron.)

An example of a physical change is the process of tempering steel to form a knife blade. A steel blank is repeatedly heated and hammered which changes the hardness of the steel, its flexibility and its ability to maintain a sharp edge.l

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Members: Dion, Joyce, Kerwin, Weijun, Sinwai

Chemical change is any change that results in the formation of new chemical substances.

Matter undergoes changes all of the time. There are two types of changes - physical and chemical. Physical changes includes melting, freezing, or changing size or shape of the object.

Four common types of chemical change are colour change, temperature change, production of gas, and formation of precipitation.

Example of chemical change: Rust forms on a nail left outside, food scraps are turned into compost in a compost pile, milk going sour, grilling a hamburger & when hydrogen peroxide bubbles in a cut.

It is also called as chemical reaction.

Sometimes compounds can come together and they can become more stable still by rearranging atoms.

These changes are called chemical reactions, and are different from the nuclear reactions we studied earlier, which are when nuclei come together (or split apart) and create new atoms

Characteristics of chemical change:

Produce new substances

Involve absorption or release of energy

Matter/mass is always conserved

Benefits and harms about chemical changes:

Nature                                                  :Rusting

Farming                                               :Burning

Manufacturing                                    :Decay of food

Cooking

Healthcare

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MEMBERS : RAGHAVI, LIRI, LYNN, SABRINA

CHEMICAL CHANGES :
● Changes that produce new substances and can't be easily reversed are called Chemical changes.
Characteristics of chemical changes:

production of new substances

release of energy

conservation of matter and mass

Chemical changes occurs through interactions with:

heat (thermal decomposition, combustion and oxidation)

light (photosynthesis and photography)

electricity (electrolysis)

mixing substances (acids + carbonates -> salt + carbon dioxide + water).

The benefits of chemical changes:

decaying and respiration of nature

farming

manufacturing

cooking

health care.

The harms of chemical changes:

rusting

burning

decay of food.

Chemical changes effects of solutions on indicators:

acids (turns blue litmus paper red, pH < 7)

alkalis (turns red litmus paper blue, pH > 7)

neutral solutions (no change with litmus paper, pH = 7).

What happens when matter & heat interacts ? :
* Thermal decomposition
-> a single substance breaks up into two or more simpler substances when it is heated .
e.g sugar -> heat -> carbon + water vapour
* Combustion
-> a substance reacts with oxygen when heated to form one or more new substances .
-> heat and light is given out
e.g when charcoal burns , carbon dioxide is produced
-> it is very common
e.g coal , natural gas &  petrol
-> usually release alot of heat energy : it is used for
> cooking
> transport
> generation of the electricity in power stations
-> word equation
petrol + oxygen -> carbon dioxide + water + heat
*Oxidation
-> it is the addition of oxygen to a substance
-> reacts only when other elements , metals and non - metals burn in air
-> when magnesium burns in air , a new substance : magnesium oxide is formed :
magnesium + oxygen -> magnesium oxide
-> the rusting of iron
the iron combines with oxygen in the air to form iron oxide or rust :
iron + oxygen -> iron oxide ( rust )
* Respiration
-> it involves oxidation
-> the word equation :
glucose + oxygen ( in living cells ) -> carbon dioxide + water + energy

What happens when matter & light interact ? :
* Photosynthesis
-> word equation
carbon dioxide + water -> light energy trapped equals chlorophyll -> gluscose + oxygen
* Photography
-> the coating on black & white photographic film contains silver bromide , exposure to light produces the dark areas on the film
-> silver bromide -> light -> sliver + bromide
the greater the exposure to ligh , the darker the area on the film

What happens when matter & electricity interacts ? :
*Electrolysis
- It is the use of electricity to cause a chemical change
-e.g. when electricity is passed through copper chloride, copper and chlorine is formed.
- It is used in the process of electroplating
- It is also used to produce many useful products such as household bleach and aluminium foil

*Electroplating
- It is the coating of an object with a thin layer of a metal.
-e.g. covering of bicycle handlebars with a thin layer of chromium or the steel parts of a car with zinc.
- This prevents the rusting of the handlebars and the car.

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Irdina , Sara , Queky , Janani

Thermal decomposition->A single substance breaks up into two or more simpler substances when it is heated
Combustion->A substance reacts with oxygen when heated to from one or more new substances
Oxidation->The addition of oxygen to a substance
Respiration- Glucose +oxygen-->carbon dioxide+water+energy
Photosynthesis- carbon dioxide+water-->glucose+oxygen
Photography- Sliver bromine-->silver+bromine
Electrolysis-> The use of electricity to cause a chemical change
Acids and metals->When dilute acids are mixed with certain metals , hydrogen gas and a salt are produced.
[hydrochloric acid+magnesium-->magnesium chloride+hydrogen gas]
Acids and carbonates-> When dilute hydrochloric acid is added to chalk , carbon dioxide gas , a salt and water are produced .
[ hydrochloric acid+ calcium carbonate-->calcium chloride+carbon dioxide gas+water ]
Acids & Alkalis-neutralisation
eg. -Toothpaste contains weak alkalis.When mixed , with the acids , a chemical reaction called neutralisation occurs.
-During neutralisation , the properties of the acid and the alkali are neutralised and help to prevent tooth decay.
pH values - tells us how acidic/alkaline a substance is
-Acids have pH values less than 7
-Alkalis have pH values greater than 7
-Some liquids are neither acidic nor alkaline .They are             neutral and have pH values of 7

Definition of chemical changes: A chemical change is a change in which a new substance is formed.

Chemical changes occur through interactions with
1)Heat-thermal decomposition
-combustion
-oxidation
2)Light-Photosynthesis
-Photography
3)Electricity-Electrolysis(electroplating)
4)Mixing substances- Acids + metals -> salt + hydrogen
- Acids + carbonate -> salt + carbon dioxide+water
-Acids + alkalis -> salt + water(neutralisation)

Chemical Changes Characteristics:
--> chemical changes produces new substances
--> involes absorption / release of energy
--> matter / mass is always conserved

Chemical Changes effects of solutions on Indicators:
(Acids)
--> turns blue litmus red
--> pH < 7
(Alkalis)
--> turns red litmus blue
--> pH > 7
(Neutral Solutions)
--> no change with litmus
--> pH = 7

Benefits:
-Nature(e.g. decay and respiration)
-Farming
-Manufacturing
-Cooking
-Healthcare

Harm:
-Rusting
-Burning
-Decay of food