Ammonia is produced in the Haber process - AQA - GCSE Chemistry - Question 7 - 2022 - Paper 2

The atom economy is determined by the ratio of the molar mass of the desired product to the total molar mass of the reactants. In this equation, all reactants (1 mole of N2 and 3 moles of H2) convert into 2 moles of NH3. Since there are no byproducts, the atom economy is calculated as: $\text{Atom Economy} = \frac{\text{Molar mass of } NH_3}{\text{Total molar mass of reactants}} = \frac{2 \times 17}{17 + 3 \times 1} = 100\%$

The mixture of NH3 and unreacted gases is cooled, allowing ammonia to liquefy as it condenses at lower temperatures. The remaining unreacted nitrogen and hydrogen gases stay in a gaseous state and can be separated through physical methods.

For Figure 5, label the x-axis to represent pressure in atmospheres, ensuring a scale from 0 to 500. Plot the remaining data points from Table 6 and mark a line of best fit to illustrate the trend in ammonia yield.

Based on the trend shown in Figure 5, one can use interpolation or extrapolation to determine the yield at 500 atmospheres. If the yield at 420 atmospheres is 43%, it is reasonable to expect that the yield at 500 atmospheres may be around 45-50%, depending on the precise trend observed.

The conditions of 450 °C and 200 atmospheres are chosen for several reasons. Higher temperatures increase the rate of reaction by providing more kinetic energy, leading to more frequent collisions. However, temperatures below 450 °C favor the formation of products due to the exothermic nature of the reaction. The pressure of 200 atmospheres is high enough to drive the reaction to the right, producing more ammonia. Furthermore, the use of a catalyst helps lower the activation energy, optimizing the reaction rate without affecting the position of equilibrium.