Practise reversible-reaction questions by interpreting ⇌, defining dynamic equilibrium and predicting yield changes from conditions.
Methanoic acid also reacts with propanol to form an ester.
The equation for the reaction is
State what is meant by the ⇌ symbol.
reaction goes both ways
Ignore:
- equilibrium
When this reaction occurs in a sealed container, the reaction can reach dynamic equilibrium.
Give one characteristic of a reaction at dynamic equilibrium.
forward and backward reactions occur at the same rate
Or:
- concentrations of reactants and products remain constant / stay the same / do not change
Allow:
- amounts / moles / ratios of reactants and products remain constant
Reject:
- concentrations of reactants and products are equal / the same
Gaseous ethanol is manufactured by reacting ethene gas with steam.
This is the equation for the reaction.
The pressure on an equilibrium mixture of the three gases is decreased. All the other conditions are kept the same.
Predict the effect of this change on the yield of ethanol at equilibrium, giving a reason for your answer.
- yield decreases and the reaction shifts towards the left-hand side
- this is the side with more moles of gas
Allow:
- backward reaction
- molecules
Predict the effect of adding a catalyst on the yield of ethanol at equilibrium, giving a reason for your answer.
- the yield of ethanol does not change
- a catalyst increases the rate of the forward and backward reactions equally