The amount of energy required to heat water for a 10-minute shower (50 gallons) is 2.2125 kj. how many calories is this?

From the problem statement, this is a conversion problem. We are asked to convert from units of kilojoules to units of calories. To do this, we need a conversion factor which would relate the different units involved. We either multiply or divide this certain value to the original measurement depending on what is asked. From literature, we will find that 1 kilojoule is equal to 239 calories. We do as follows:

2.2125 kJ ( 239 calories / 1 kJ ) = 528.79 calories