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

Question

Quizplus · Accepted Answer

To calculate the energy removed to turn water at 0°C into ice, we use the formula: Energy = mass × latent heat of fusion of water. The latent heat of fusion of water is approximately 334 kJ/kg. Therefore, for 0.25 kg of water, the energy removed is 0.25 kg × 334 kJ/kg = 83.5 kJ to turn it into ice. However, since the water is initially at 20°C, we must first cool it to 0°C before it can freeze. The specific heat capacity of water is approximately 4.18 kJ/(kg·°C). Thus, the energy removed to cool the water from 20°C to 0°C is 0.25 kg × 4.18 kJ/(kg·°C) × 20°C = 20.9 kJ. Adding these two amounts gives the total energy removed: 83.5 kJ + 20.9 kJ = 104.4 kJ, which is approximately 104 kJ.

A Container Holding 0 ∘\circ∘ C Is Placed into the Freezer

A Container Holding 0 $\circ$ C Is Placed into the Freezer