Question

show all of your work for full marks (aoking problems, including units, scientific notation, significant figures, etc. 1. on a cold february day, you wonder why lake ontario is still not frozen, despite a long, cold winter. explain why the lake is not frozen and describe the thermodynamic property responsible for this phenomenon. ( /2)

Explanation:

Lake Ontario doesn't freeze easily due to its large volume of water. The thermodynamic property responsible is heat capacity (specifically, the high specific heat capacity of water). Water has a high specific heat, meaning it requires a large amount of heat energy to change its temperature (or to freeze, as freezing involves a phase change with associated latent heat). The large mass of water in the lake means a huge amount of heat must be removed (cooled below 0°C and then latent heat of fusion removed) for it to freeze. Even a long cold winter may not provide enough time/heat removal to freeze such a large body of water. Also, water's density anomaly (max density at 4°C) causes mixing, delaying freezing as surface water cools, becomes denser, sinks, and is replaced by warmer water from below, slowing the overall cooling and freezing process.

Answer:

The thermodynamic property responsible is the high specific heat capacity (and density anomaly) of water. The large volume of water in Lake Ontario requires a massive amount of heat to be removed to cool it to 0°C and then to freeze (due to latent heat of fusion), and water's density anomaly (max density at 4°C) causes mixing, slowing cooling. Thus, a long cold winter may not provide enough heat removal for it to freeze.