Principles of dynamic equilibrium
Higher tier only
- Reaction conditions such as temperature and pressure affect the rate of a reaction
- If the reaction is reversible then the position of equilibrium is also affected by changes in these conditions and often we must consider a trade-off between the rate of reaction and product yield
- The graph below illustrates the effects of changing temperature and pressure on the yield of ammonia obtained
- By following any of the curved lines on the graph it can be seen that as the pressure increases, so too does the yield at any given temperature
- By following any vertical line upwards from the x-axis, the graph shows that as the temperature decreases, the yield actually increases
- The actual conditions used must be chosen depending on a number of economical, chemical and practical considerations
The yield of ammonia produced changes with changes made to temperature and pressure
Examiner Tip
Remember dynamic equilibrium only applies to a reversible reaction occurring in a closed vessel.
