Ethanol, C2H5OH\text{C}_2\text{H}_5\text{OH}C2H5OH, can be prepared industrially by the hydration of ethene with steam, as shown in equilibrium 2.
C2H4(g)+H2O(g)⇌C2H5OH(g)ΔH=−45 kJ mol−1Equilibrium 2 \text{C}_2\text{H}_4\text{(g)} + \text{H}_2\text{O(g)} \rightleftharpoons \text{C}_2\text{H}_5\text{OH(g)} \quad \Delta H = -45 \text{ kJ mol}^{-1} \quad \text{\textbf{Equilibrium 2}} C2H4(g)+H2O(g)⇌C2H5OH(g)ΔH=−45 kJ mol−1Equilibrium 2Predict the conditions of pressure and temperature that would give the maximum equilibrium yield of C2H5OH\text{C}_2\text{H}_5\text{OH}C2H5OH in equilibrium 2. Explain your answer.
A catalyst is used in the industrial production of ethanol 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 | C2H4(g)\text{C}_2\text{H}_4\text{(g)}C2H4(g) | H2O(g)\text{H}_2\text{O(g)}H2O(g) | C2H5OH(g)\text{C}_2\text{H}_5\text{OH(g)}C2H5OH(g) |
|---|---|---|---|
| Sθ / J K−1mol−1S^\theta \text{ / J K}^{-1}\text{mol}^{-1}Sθ / J K−1mol−1 | 219 | 189 | 282 |
A chemist proposed producing ethanol at 450 K450 \text{ K}450 K using equilibrium 2. Explain, with a calculation, whether the production of ethanol is feasible at 450 K450 \text{ K}450 K.
At 298 K298 \text{ K}298 K, the free energy change, ΔG\Delta GΔG, for the production of ethanol in equilibrium 2 is −8.10×103 J mol−1-8.10 \times 10^3 \text{ J mol}^{-1}−8.10×103 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.
