When lead (II) oxide, PbO, is allowed to react with oxygen, O₂, at a temperature of 823 K and standard pressure through the reaction
PbO(s) + ½O₂(g) ∏ PbO₂(s)
The partial pressure of oxygen at equilibrium is 11.6 Pa. Determine the standard Gibbs energy of reaction at this temperature.

Question

Quizplus · Accepted Answer

The standard Gibbs energy of reaction can be calculated using the equation ΔG° = -RTlnKp, where R is the gas constant (8.314 J mol^-1 K^-1), T is the temperature in Kelvin, and Kp is the equilibrium constant related to the partial pressures of the gases involved. Given the partial pressure of oxygen at equilibrium is 11.6 Pa, and since the reaction involves ½ mole of O2, Kp = (P_O2)^1/2 = (11.6 Pa)^1/2. Plugging the values into the equation and converting units appropriately gives a ΔG° close to -31.0 kJ mol^-1, making choice A correct.

When Lead (II) Oxide, PbO, Is Allowed to React with Oxygen