Question

If 200g of water is 30°C in a tray and gets changed into water at 0°C when it is placed inside the deep freezer of a refrigerator for some time, what is the heat released?

Answer 1

To calculate the heat released when water changes from 30°C to 0°C, you need to consider the specific heat capacity of water and the latent heat of fusion.

1. Heating the water from 0°C to its freezing point of 0°C: The specific heat capacity of water is approximately 4.18 Joules/gram°C. Therefore, the heat required to raise the temperature of 200g of water from 0°C to 0°C is:

Q1 = mass × specific heat capacity × temperature difference = 200g × 4.18 J/g°C × (0°C - 0°C) = 0 Joules

No heat is required or released during this phase since the temperature remains constant.

2. Freezing the water at 0°C: The latent heat of fusion for water is approximately 334 J/g. Therefore, the heat released during the phase change from water at 0°C to ice at 0°C is:

Q2 = mass × latent heat of fusion = 200g × 334 J/g = 66,800 Joules

So, the total heat released when 200g of water at 30°C is changed into water at 0°C inside the deep freezer is 66,800 Joules.