Which will cool the water more: a piece of ice or the same mass of water at 0 ° C.

Ice has the heat capacity of ice equal to 2100 J / kg * s, while the specific heat of water is twice as much as 4200 J / kg * s. But ice has a specific heat of 340,000 J / kg, which means that the ice will completely take 34,000 J from the water in order to melt, which is much more than 4200 J, therefore the ice will cool the water much more.