Specific heat capacity of ice = 2100 J kg-1 K-1, Specific heat capacity of water is 4200 J kg-1 K-1.
Solution:
According to the question, 1 kg of ice at -10oC is completely converted into water at 100oC. Using the expression for heat energy i.e., Q = m × c × (change in temperature), we can write the expression for heat energy gained by 1 kg of ice at – 100 C in order to raise its temperature to 00 C is
= 1 × 2100 × 10 = 2100 J
Similarly, heat energy gained by 1 kg of ice at 00 C in order to convert into water at 00 C = L
Then, the heat energy gained when the temperature of 1 kg of water at 00 C rises to 1000 C is
= 1 × 4200 × 100 = 420000 J
Therefore, the total amount of heat energy gained
= 21000 + 420000 + L = 441000 + L
It is given that the total amount of heat gained is 777000 J
So, 441000 + L = 777000
Or, we can write => L = 777000 – 441000
Thus, L = 336000 J kg-1