The temperature–time graph for a supercooled aqueous solution shows the temperature decreasing from 5 °C to −8 °C before suddenly rising to 0 °C and then remaining constant for a short interval. Which explanation most consistently accounts for the sudden temperature increase observed at −8 °C?
a) Hydrogen bonds in the liquid stretch and break below −8∘C, and this bond breaking releases heat that warms the solution to 0∘C.
b) The solution begins to freeze at −8∘C, releasing latent heat that raises the temperature to the equilibrium freezing point.
c) The specific heat capacity of water decreases sharply below 0∘C, so with the same rate of heat input the temperature rises more quickly to 0∘C.
d) The increased density of water as it cools mechanically compresses the liquid, converting work into heat that raises the temperature to 0∘C.