Physics 2012 JAMB Past Questions - Question 24: The quantity of heat energy required to melt completely 1kg of ice at -300�C is

Correct Answer

B

Explanation

The quantity of heat energy required to melt completely 1kg of ice at -300°C can be calculated using the specific heat capacity and latent heat of fusion of ice. The specific heat capacity of ice is approximately 2.09 J/g°C, and the latent heat of fusion of ice is approximately 334 J/g.

To convert the mass of ice from kilograms to grams, we multiply by 1000. So, 1kg of ice is equal to 1000g.

First, we need to calculate the heat energy required to raise the temperature of the ice from -300°C to 0°C:

Q1 = mass × specific heat capacity × temperature change
  = 1000g × 2.09 J/g°C × (0°C - (-300°C))
  = 1000g × 2.09 J/g°C × 300°C
  = 627,000 J

Next, we calculate the heat energy required to melt the ice at 0°C:

Q2 = mass × latent heat of fusion
  = 1000g × 334 J/g
  = 334,000 J

Finally, we add the two quantities of heat energy together to get the total heat energy required:

Total heat energy = Q1 + Q2
                = 627,000 J + 334,000 J
                = 961,000 J

Therefore, the quantity of heat energy required to melt completely 1kg of ice at -300°C is 961,000 Joules.