In the previous century, the Haber process was sometimes carried out at pressures of $1000\,\text{atm}$ and above. At present, it is usually carried out at pressures below $100\,\text{atm}$. What explains this change?
- AAn iron catalyst is used.
- BMaintaining the higher pressures is more expensive.
- CThe equilibrium yield of ammonia is increased at lower pressures.
- DThe rate of the reaction is increased at lower pressures.