Methanol, CH3OH\text{CH}_3\text{OH}CH3OH, can be prepared industrially by the catalytic hydrogenation of carbon monoxide, as shown in equilibrium 2.
CO(g)+2H2(g)⇌CH3OH(g)ΔH=−91 kJ mol−1Equilibrium 2 \text{CO(g)} + 2\text{H}_2\text{(g)} \rightleftharpoons \text{CH}_3\text{OH(g)} \quad \Delta H = -91 \text{ kJ mol}^{-1} \quad \text{\textbf{Equilibrium 2}} CO(g)+2H2(g)⇌CH3OH(g)ΔH=−91 kJ mol−1Equilibrium 2Predict the conditions of pressure and temperature that would give the maximum equilibrium yield of CH3OH\text{CH}_3\text{OH}CH3OH in equilibrium 2. Explain your answer.
A catalyst is used in the industrial production of methanol in equilibrium 2. State two ways that the use of catalysts helps chemical companies to make their processes more sustainable and less harmful to the environment.
Standard entropy values are given in the table below.
| Substance | CO(g)\text{CO(g)}CO(g) | H2(g)\text{H}_2\text{(g)}H2(g) | CH3OH(g)\text{CH}_3\text{OH(g)}CH3OH(g) |
|---|---|---|---|
| Sθ / J K−1mol−1S^\theta \text{ / J K}^{-1}\text{mol}^{-1}Sθ / J K−1mol−1 | 198 | 131 | 240 |
A chemist proposed producing methanol at 500 K500 \text{ K}500 K using equilibrium 2. Explain, with a calculation, whether the production of methanol is feasible at 500 K500 \text{ K}500 K.
At 298 K298 \text{ K}298 K, the free energy change, ΔG\Delta GΔG, for the production of methanol in equilibrium 2 is −2.54×104 J mol−1-2.54 \times 10^4 \text{ J mol}^{-1}−2.54×104 J mol−1.
ΔG\Delta GΔG is linked to KpK_pKp by the relationship: ΔG=−RTlnKp\Delta G = -RT \ln K_pΔG=−RTlnKp.
R=8.314 J mol−1K−1R = 8.314 \text{ J mol}^{-1}\text{K}^{-1}R=8.314 J mol−1K−1 T=temperature in KT = \text{temperature in K}T=temperature in K.
Calculate KpK_pKp for equilibrium 2 at 298 K298 \text{ K}298 K. Give your answer to 3 significant figures and state its units, assuming partial pressures are measured in atm\text{atm}atm.
