Summary Chemical Equilibria A level Chemistry AQA

1




1. High temperature
2. The position of the equilibrium shifts left to the right in the
endothermic direction
3. To decrease the temperature




1. Increases the rate of reaction
2. High pressure means that there are more particles in a given
volume and more collisions in a given time




(iii) A nickel catalyst is used in the first stage.

Explain why the catalyst is more effective when coated onto an unreactive
honeycomb.


1. Increases the surface area
2. So there are more successful collisions in a given time on the
surface of the catalyst with the nickel

, 2




1. No effect
2. There is an equal number of moles on either side of the equation




units = mol−1 dm3




No effect

, 3




Effect: Increase of SO3

Explanation:

1. There are fewer moles on the right hand side
2. so the equilibrium shifts to the right to try reduce the pressure
3. to keep Kc constant

, 4


1. The hydroxide ions reacts with the acid
2. So the equilibrium shifts to the right




Explain why chlorine is used to kill bacteria in swimming pools, even
though chlorine is toxic.



1. Only used in small amounts
2. Health benefits outweigh the risks




1. Darkened / went more orange
2. The equilibrium moved to the right
3. To oppose the increased concentration of Y




The student warmed the equilibrium mixture from part (c).
Predict the colour change, if any, when the equilibrium mixture was
warmed.



The orange colour would fade