Equilibrium and Reversible Reactions

What is a reversible reaction?

A reaction in which the direction of the reactions can change due to the surrounding conditions of the reaction

Give two common reversible reactions

1) Copper (II) sulphate + water ⇌ hydrated copper (II) Sulphate

Chemial formula: CuSO4 + 5 H20 ⇌ CuSO4 ⋅ 5H20

The forwards reaction (exothermic )changes from white to blue

2) Cobalt (II) chloride + water ⇌ hydrated cobalt (II) chloride

Chemical formula: CoCl2 + 6H20 ⇌ CoCl2 ⋅ 6H20

Colour change forwards (exothermic) is blue to pink

Define ‘hydrated’ and ‘anhydrous’

Hydrated → a compound that contains water molcules in its crystalline structure

Anhydrous → a compound that does not contain water molecules in its crystalline structure

What do we mean when a reaction has reached ‘equilibrium’?

The rate of the forwards reaction is equal to the rate of the reverse reactions so that the concentration of products and reactants no longer changes

(every time two reactants collide to form a product, another product breaks apart to form two reactants)

What is the rule of making changes in a reversible reaction?

When you make a change in a reversible reaction, the state of equilibrium will shift to counter the change

How does increasing temperature affect the rate of equilibrium?

→ The endothermic reaction is favoured to take in the heat being added to counter the change (therefore if the forwards reaction is endothermic you will recieve a higher yield of product)

How does increasing the pressure affect equilibrium?

• Increasing the pressure of a reversible reaction forces more gas molecules into the container = more molecules will be present

• The equilibrium will shift in favour of the forwards reaction to counter the increase in particles creating more products as there are less of the product than the reactant

How does changing the concentration of the reactants affect the equilibrium?

• Increasing the concentration of the reactants will favour the forwards reaction to produce a higher yield of product to increase the concentration of the product

How does a catalyst affect the equillibrium?

• The catalyst just increases the rate of both reactions and the equilibrium does not move

How can we increase the yield of a revesrible reaction if the forward reaction is exothermic?

• Decreasing the tempeature

• Increasing the Pressure

• Increasing the conc of reactant