how much energy (in J) was made unavailable for useful work as a result?

Question

An irreversible process takes place by which the entropy of the universe increases by 1.66 J/K. If the temperature of the environment in which the process occurred is 230 K, how much energy (in J) was made unavailable for useful work as a result?

Answer 1

If the temperature remains constant during the process (as in this case),

then the unavailable energy is the product of the temperature and the increase in entropy.

230 K x 1.66 J/K = 381.8 J