Reversible Reactions .2

what are reversible reactions

In some chemical reactions, the products of the reaction can react together to produce the original reactants

how are reversible reactions represented

A + B ⇌ C + D

what is an example of a reversible reaction

Ammonium chloride is a white solid

what happens when Ammonium chloride is heated

• It breaks down when heated, forming ammonia and hydrogen chloride.

• When these two gases are cool enough, they react together to form ammonium chloride again.

what can the reversible reaction for Ammonium chloride be modelled as

This reversible reaction can be modelled as:

ammonium chloride ⇌ ammonia + hydrogen chloride

NH₄Cl(s) ⇌ NH₃(g) + HCl(g)

If a reaction is exothermic in one direction…

it will be endothermic in the other direction.

what is the same about the forwards and reverse reaction

The same amount of energy is transferred in both the forwards and reverse reaction.

what is Blue copper sulfate described as

hydrated

what is the forward reaction of Blue copper sulfate

The forward reaction is endothermic and the reverse reaction is exothermic.

what happens when a reversible reaction happens in a closed container

it reaches a dynamic equilibrium.

what happens at equilibrium (3)

At equilibrium:

• the forward and backward reactions are still happening

• the forward and backward reactions have the same rate of reaction

• the concentrations of all the reacting substances remain constant

what is the equilibrium position of a reversible reaction is a measure of

the concentrations of the reacting substances at equilibrium

what does the haber process involve and state what type of reaction it is

Nitrogen gas is reacted with hydrogen gas to make ammonia gas. The forward reaction is exothermic.

N₂(g) + 3H₂(g) ⇌ 2NH₃(g)

what is the equilibrium position of the haber process

The equilibrium position is:

• to the left if the concentrations of N₂ and H₂ are greater than the concentration of NH₃

• to the right if the concentration of NH₃ is greater than the concentrations of N₂ and H₂

what does Le Chatelier's principle state (3)

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

• changing the pressure

• changing the concentration

• changing the temperature

what happens when a change is made to a system at equilibrium

the position of equilibrium moves to counteract the change that was made

when a temperature is increased what happens to the position of equilibrium

if the temperature is increased, the position of equilibrium moves in the endothermic direction to reduce the temperature.

If the pressure is increased in a reaction involving gases…

the equilibrium position moves in the direction of the fewest molecules of gas, to reduce the pressure.

what is important to know about the haber process and how is the position of equilibrium affected

There are fewer molecules on the right-hand side of the equation for the Haber process:

N2⁡(g)+3⁢H2⁡(g)⇌2⁢N⁡H3⁡(g)

1+3=4 m⁢o⁢l⁢e⁢c⁢u⁢l⁢e⁢s. 2 m⁢o⁢l⁢e⁢c⁢u⁢l⁢e⁢s

If the pressure is increased, the equilibrium position moves to the right.

what happens in the haber process if the temperature increases (due to the fact that the forward reaction is exothermic, the backward reaction is endothermic)

• if the temperature is increased,

• the equilibrium position moves in the endothermic direction (to the left) to reduce the temperature

• This means that less ammonia (NH₃) will be produced

If the concentration of a reactant (on the left) is increased…

the equilibrium position moves in the direction away from this reactant, and so more of the products are produced (on the right)

Changing the concentration using the reaction between bismuth chloride reacting with water in a reversible reaction - how can the concentration of hydrochloric acid be increased and what happens to the equilibrium position

• can be increased by adding more hydrochloric acid.

• When this happens, the equilibrium position moves to the left, away from HCl(aq) in the equation.

BiCl₃(aq) + H₂O(l) ⇌ BiOCl(s) + 2HCl(aq)