Why is it that, in cold winters, a tub of water placed in a farmer's canning cellar helps prevent freezing?

Question

Why is it that, in cold winters, a tub of water placed in a farmer's canning cellar helps prevent canned food from freezing?

Answer 1

When liquid water changes to ice, heat is released to the air around it. This warms the air, keeping the temperature above freezing.

Think of it this way:

To change ice to liquid water, you need to add heat to the ice.
ice + heat ---> liquid water

So, the reverse reaction must release heat
liquid water ---> ice + heat