How much heat is necessary to change 10 g of ice at -20°C into water at 10°C?
A) 0.02 kcal
B) 0.2 kcal
C) 1 kcal
D) 0.08 kcal

Question

Quizplus · Accepted Answer

To change 10 g of ice at -20°C into water at 10°C, we need to calculate the heat required in three steps: heating the ice from -20°C to 0°C, melting the ice into water at 0°C, and then heating the water from 0°C to 10°C. The specific heat of ice is approximately 0.5 kcal/kg°C, the heat of fusion of ice is 80 kcal/kg, and the specific heat of water is 1 kcal/kg°C. 1. Heating the ice from -20°C to 0°C: $10 g \times 0.5 kcal/kg°C \times 20°C = 10 kcal/kg \times 0.02 kg = 0.2 kcal$2. Melting the ice into water at 0°C: $10 g \times 80 kcal/kg = 800 kcal/kg \times 0.01 kg = 8 kcal$3. Heating the water from 0°C to 10°C: $10 g \times 1 kcal/kg°C \times 10°C = 10 kcal/kg \times 0.01 kg = 0.1 kcal$Adding these together: $0.2 kcal + 8 kcal + 0.1 kcal = 8.3 kcal$However, none of the provided options match the correct calculation. It seems there might have been a misunderstanding in the calculation or the options provided. Based on typical values and the process described, the actual amount of heat required would be more than any of the options listed, suggesting a possible error in the question or the answer choices.

How Much Heat Is Necessary to Change 10 G of Ice