Reversible reactions by Mahua GANGULY

Features of an equilibrium reaction

sabrina_wong17 — 2021-09-20 02:18:17 UTC

1. It is dynamic. This means that the reactants and products are changing into each other constantly at the same rate.

2. The concentrations of the reactants or products are the same.

3. The reaction takes place in a closed system, where neither of the products are able to escape from the system.

Q: Are equilibrium reactions reversible or irreversible?
A: It depends. If the reaction takes place in an open system, it is irreversible since some products could escape from the system. If the reaction takes place in a closed system, it is reversible since the reactants and products remain in the same location.

Q: Changing the temperature of an equilibrium reaction?
A: When the temperature of a reaction increases, the equilibrium shifts in the endothermic direction. When the temperature of a reaction decreases, the equilibrium shifts in the exothermic direction. You can tell if an equilibrium reaction is exothermic or endothermic based on the enthalpy level given at the end of a chemical equation.

Q: Changing the pressure of an equilibrium reaction?
A: When the pressure of a reaction increases, the equilibrium shifts towards the side of the equation with fewer molecules.
When the pressure of a reaction decreases, the equilibrium shifts towards the side of the equation with more molecules.
If the pressure is changed for a reaction where the number of molecules on both sides are equal, there will be no effect on the reaction.

Q: Changing the concentration of an equilibrium reaction?
A: When the concentration of the reactants increases, the equilibrium shifts to the products. When the concentration of the products increases, the equilibrium shifts to the reactants.

Q: Adding a catalyst to an equilibrium reaction?
A: Adding a catalyst reduces the amount of activation energy and the time it takes to reach equilibrium. But it doesn't change the position of the equilibrium.

Q: What are some examples of reversible reactions?
A: 1. When blue hydrated copper sulphate is heated to form white anhydrous copper sulphate and water, like this:
CuSO4 * 5H2O = CuSO4 + 5H2O
2. When water is added to blue anhydrous cobalt chloride to form pink hydrated cobalt chloride, like this:
CoCl2 + 6H2O = CoCl2 * 6H2O

Q: What is the Haber process?
A: When you combine nitrogen and hydrogen molecules to make ammonia, the rate of forward reaction is usually the highest since the concentration of the reactants are the highest. But as the reaction proceeds, the concentration of the reactants decreases as they are used up to make ammonia. This means the concentration of ammonia increases. Soon, the reaction reaches an equilibrium. This can be graphed in the shape of a sideways Y.
(N2 + 3H2 = 2NH3) + iron catalyst + 200 atp + 450 degrees celsius

Q: What is the Contact process?
A: When sulphur dioxide and oxygen are combined to make sulphur trioxide. This is an exothermic reaction, meaning that a lower temperature would be more favourable, however this would mean the reaction would take longer. Instead, a compromise temperature of 450 degrees celsius is used and this provides a good yield. Exothermic reactions mean that a higher pressure is better, but a small increase in pressure is also good since sulphur dioxide is very reactive. Using the catalyst, vanadium penta-oxide, the % of sulphur trioxide are the same but the yield may decrease.

- Sabrina

some examples of reversible change

2021-09-20 02:31:03 UTC

Melting: Melting is when solid converts into a liquid after heating. An example of melting is the turning of ice into water.
Freezing: Freezing is when a liquid converts into a solid. An example of freezing is the turning of water into ice.
Boiling: Boiling is when a liquid converts into a gas.

The equilibrium position can be changed by changing the reaction conditions through:

changing the pressure
changing the concentration
changing the temperature

In a reversible reaction, both forward and reverse directions of the reaction generally occur at the same time. While reactants are reacting to produce products, products are reacting to produce reactants. Often, a point is reached at which forward and reverse directions of the reaction occur at the same rate.
For reversible reactions, either the forwards or backward reaction will be exothermic, and the other will be endothermic. When we increase the temperature, the reaction will favor whichever reaction is endothermic to take in heat and reduce the temperature.

jasmine

What is Dynamic Equilibrium

kyle_ling17 — 2021-09-20 02:31:03 UTC

The dynamic Equilibrium is when the rate of the forward reaction and the rate of the backward reaction happens at the same time, meaning that both of the reactions are happening at the same rate and the concentration of the product and the reactants stays the same.
-Kyle

le chatelier's principle

2021-09-20 02:32:28 UTC

whan a change is made to the conditions of a system at equilibrium, the system automatically move to oppose the change.
- it is used to predict changes to the position of equilibrium.

- Vision

Changing the temperature, when forward reaction is exothermic and backward reaction is endothermic

2021-09-20 02:32:57 UTC

Increase temperature, equilibrium shift to left hand side, rate of reaction is increased

Decrease temperature, equilibrium shift to right hand side, rate of reaction is decreased as it took more time to reach equilibrium.

E.g. I2+H2 -> 2HI
When temperature increased, the reaction get faster to reach equilibrium, hence more reactant, less product

-Wilbur

Equilibrium Definition

200043675 — 2021-09-20 02:33:36 UTC

The RATE of the forward reaction equals to the RATE of the reverse reaction.

It can be dynamic, which the reaction is continuing, but the status and concentration of the whole reaction is constant.
-- Caspar

Equilibrium

2021-09-20 02:34:48 UTC

When a reversible reaction is in equilibrium state, anything changed no matter product or reactants, the reaction changes and tries to restore equilibrium, forming a new mixture of equilibrium. The reaction can be changed by changing temperature, pressure, concentration and catalyst

Alvin

Effect of changing the conditions

2021-09-20 02:36:29 UTC

Increase temperature, the equilibrium position will shift to the right. This is the direction of the endothermic reaction.

Decrease temperature, the equilibrium position will shift to the left. This is the direction of the exothermic reaction.

Jenny

What will shift the equilibrium?

2021-09-20 02:37:08 UTC

Increase temperature ( shift to the left-hand side if the forward reaction is exothermic the backward reaction will be endothermic)
Increase pressure (shift to the side which has lesser moles)
Increase concentration
Ben

Graph showing the use of catalyst in a reversible reaction

feiyiching18 — 2021-09-20 02:37:15 UTC

When the catalyst is added, the rate of reaction would be increased by reducing the activation energy (AE)
a catalyst is a substance added to speed up which would not be used up.

Faye

Shifting the equilibrium

2021-09-20 02:37:24 UTC

-When temperature increase, the reaction shift to the reactants.
-When the temperature increase, the equilibrium will shifted to the right.
-Dynamic means there is a continual change while new ones form.
-Endothermic is energy is absorbed and heat from the surrounding which causes the temperature to decreased.
-Exothermic is energy is released and heat energy to the surrounding which causes the temperature to increase.
Jingwen Huang

Exo & Endothermic Reaction

200043675 — 2021-09-20 02:37:28 UTC

- Exothermic is the release of the energy to the surrounding
- Endothermic is the absorbed of the energy from the surrounding.
- All neutralisation reaction are exothermic
- Few reactions are endothermic
- Making chemical bonds is alway exothermic
- Breaking chemical bonds is always endothermic
- Lower temp. favours exothermic
- Higher temp. favours endothermic

-- Caspar

Reversible reaction and equilibrium

2021-09-20 02:38:29 UTC

Reversible reaction is endothermic in one direction it can have forward reaction and backwards reaction. Example for this can be copper(ll) sulfate. Equilibrium is when the rate of forward reaction equals to the rate of the backward reaction and the factors that can effect the equilibrium are the concentration of the reaction, temperature, pressure, catalyst and lastly the speeding of the reaction.
- Annie

Shifting the equilibrium

200034972 — 2021-09-20 02:38:30 UTC

1. Change the temperature
When the temperature increases, the equilibrium shifts to the right when the forward reaction is endothermic.
2. Change the pressure
When the temperature increases, the equilibrium shifts to the product side.
3. Catalyst
Add catalyst could speed up the reaction and lower the activation energy.

Yvonne

chakshingchung17 — 2021-09-20 02:39:26 UTC

Sulfuric Acid is a very nice substance because it is very versatile and dangerous. Therefore we have devised a way to make sulfuric acid.

Materials: Sulfur, air, water.

1. Sulfur is first burned in air to form sulfur dioxide, which is a pollutant. But it is also a crucial material for making Sulfuric acid.(It is commonly obtained via metal sulphide ores, e.g: Zinc Sulfide, Copper Sulfide)

S+O2 -> SO2

The next process is the oxidation reaction of sulfur dioxide to form sulfuri trioxide. This reaction is reversible.

2SO2+O2 <-> 2SO3

Conditions:
- Catalysts known as Vanadium(V) oxide is used to increase the rate. The dioxide pass through several beds of it to be catalysed However, rate of forward reaction equals to the rate of backwards reaction.
-The forward reaction is exothermic, but Vanadium(V) oxide sleeps under 400 degrees celsius and the rate will be slow if temperature is too slow, so a temperature of 450 degrees celsius is used.(exothermic reaction favours low temperature
-The L.H.S chemicals has more molecules(3) than the R.H.S chemicals(2), so pressure is increased to increase the yield. as less molecules favours high pressure.
But pressure is only increased a little because it is expensive and dangerous.
-SO3 is continuously removed so new ones will form

When trioxide is formed, it is dissolved into conc. sulphuric acid to form a oily substance known as oleum.(H2S2O7)

Oleum is then mixed carefully with water to form sulphuric acid.

H2O + SO3 -> H2SO4.

Done :)

-Tony