Halliday, Resnick & Walker — Entropy and the Second Law of Thermodynamics: Problem 19

19 Energy can be removed from water as heat at and even below the normal freezing point ($0.0^\circ\text{C}$ at atmospheric pressure) without causing the water to freeze; the water is then said to be supercooled. Suppose a $1.60\text{ g}$ water drop is supercooled until its temperature is that of the surrounding air, which is at $-10.0^\circ\text{C}$. The drop then suddenly and irreversibly freezes, transferring energy to the air as heat. What is the entropy change for the drop? (Hint: Use a three-step reversible process as if the water were taken through the normal freezing point.) The specific heat of ice is $2220\text{ J/kg}\cdot\text{K}$.