A 2kg block of ice initially at T = −20◦C is put in contact with a very large amount of liquid water at T = 0◦C (by “very large amount” we imply that by the time ice and water reach thermal equilibrium, there will still be some liquid water left). Ice and water can exchange heat just with each other but not with the environment. The specific heat of water is 4186  and of ice 2050 J.

Find the final mass of ice in the system at equilibrium