Question

A container holding 0.25 kg of water at 20.0c is placed into the freezer. How much energy must be removed from the water to turn into ice?

Answer 1

Heat capacity c = 4200 J/kg K

To let the water freeze, it needs to cool down to 0 degrees

Heat Q=cm(∆t) = 4200∙0.25∙20=21000 J=21 kJ