The Haber Process - Trade-Offs
Chemistry: AQA GCSE Higher, topic 10.4.4
Trade-Offs in the Haber Process
The reaction that produces ammonia in the Haber process is reversible. Because of this, changing the conditions affects the position of equilibrium.
What temperature is used in the Haber process?
- The forward reaction is exothermic. This means that an increase in temperature moves the position of equilibrium towards the reactants.
- So, there is a trade-off between increasing the rate of reaction by increasing the temperature and reducing the yield (because of the high temperature).
- As we have already seen, the end compromise is that a temperature of 450°C is used.
What pressure is used in the Haber process?
- There are fewer molecules of product than reactant. This means that an increase in pressure moves the position of equilibrium towards the products.
- Increasing the pressure also increases the rate of reaction, but high pressures are expensive and can be hazardous. 200 atmospheres represents a happy medium between rate of ammonia production versus safety and cost.
Test yourself on The Haber Process - Trade-Offs
Which of these statements about the Haber process equilibrium is correct?
Why is 450°C used as a compromise temperature in the Haber process rather than a higher temperature?
In the Haber process, which of the following is NOT a negative consequence of increasing the pressure?
Why might the conditions used in the Haber process change slightly over time?
In the Haber process, what effect does increasing the pressure have on the rate of reaction, in addition to shifting the equilibrium towards the products?