The following reaction is used industrially to produce a combustible gas from coal:

1. The following reaction is used industrially to produce a combustible • gas from coal: • H2O(g) + C(s) H2(g) + CO(g) • A mixture of powdered coal and steam at a pressure of 1 atm and a • temperature of 1300 oC was allowed to reach equilibrium. It was found that • he total pressure had increased to 1.9 atm but the remaining steam had a partial • pressure of only 0.1 atm. • Write down the expression Kp including its units. • Use the data given to calculate the partial pressures of hydrogen and carbon monoxide and hence calculate a value for Kp

2. Kp = PH2 x PCO PH20 • H2O(g) + C(s) H2(g) + CO(g) • 0 0 • 0.1 0.9 0.9 Initial partial pressure/atm: Equilibrium: Change in partial pressure of steam = 1 – 0.1 = 0.9 atm. The steam has reacted to form hydrogen and carbon monoxide Since 1 mol of steam produces 1 mol of H2 and 1 mol of CO, partial pressure of H2 = partial pressure of CO = partial pressure of steam used = 0.9 atm. Kp = PH2 x PCO = 0.9 x 0.9 = 8.1 0.1 PH20

3. Alternative method: Since the total pressure at equilibrium is 1.9 and the remaining partial pressure of steam is 0.1, the partial pressures of H2 and CO is 1.9 – 0.1 = 1.8. Since the same amounts of H2 and CO are produced in the reaction, partial pressure of H2 = partial pressure of CO = 0.5 x 1.8 = 0.9 atm.