Chapter 51

Explain why \(\Delta H\) is positive for the melting of ice.

Do you expect \(\Delta S\) to be positive or negative for the melting of ice? Explain your reasoning.

Consider the freezing of water: \(\mathrm{H}_{2} \mathrm{O}(\ell) \rightleftharpoons \mathrm{H}_{2} \mathrm{O}(\mathrm{s})\). a) Will \(\Delta H\) be positive or negative? b) Will \(\Delta S\) be positive or negative? c) Explain your reasoning for both of your answers.

Under what conditions can an endothermic reaction occur naturally? Explain your reasoning.