A slice of pizza has 500 kcal. If we could burn the pizza and use all the heat to warm a 50-L container of cold water, what would be the approximate increase in the temperature of the water? (Note: A litre of cold water weighs about 1 kg.)

Question

Quizplus · Accepted Answer

The specific heat capacity of water is 4.18 J/g°C (or 4.18 kJ/kg°C). We can first convert the calories in the pizza to joules:

500 kcal × 4.18 kJ/kcal = 2090 kJ

Since all the heat is transferred to the water, we can calculate the amount of energy required to raise the temperature of 50 kg of water (50 L of water) by 1°C:

50 kg × 4.18 kJ/kg°C = 209 kJ

Dividing the total energy by the energy required to raise the temperature of the water by 1°C:

2090 kJ ÷ 209 kJ/°C ≈ 10°C

Therefore, the approximate increase in the temperature of the water would be 10°C.

A Slice of Pizza Has 500 Kcal