23. The Second Law of Thermodynamics

Freezing a kilogram of water, initially at 20°C, requires your refrigerator to remove about $417\mathrm{kJ}$ of thermal energy from the water. If the coefficient of performance of your refrigerator is 5.0, how much heat is exhausted into your kitchen when you freeze a kilogram of water?

What is the maximum possible coefficient of performance for a refrigerator operating between 2.0°C (a typical refrigerator temperature) and 20°C (a typical kitchen temperature)?