The standard reaction enthalpy of zn(s) + h2o(g) →zno(s) + h2(g) is known to be hr 0 = 224 kj and is approximately constant from 920 k up to 1280 k. the standard reaction free energy is +33 kj at 1280 k. calculate the equilibrium constant at 1280 k and then calculate the temperature at which the equilibrium constant becomes greater than 1.

K = 0.0450, T > 1501 K

Explanation:

We may apply the Gibbs free energy equation relating the Gibbs free energy to an equilibrium constant of a reaction. The relationship is described by the following equation:

Rearrange the equation for the equilibrium constant:

Given the temperature and the ideal gas law constant  , we obtain:

Now notice if , then and .

We may firstly solve for the entropy change of this reaction using the following equation:

Using the same equation, solve when the change in the Gibbs free energy is negative: