Question

A vessel with a negligible heat capacity contains 1000 g of ice at 0°C. Into it is poured 100 g of water at 100°С. What would be the result at the end of the experiment?

[SHC of water = 4.2 Jg⁻¹°C⁻¹ and SLH of ice = 336 Jg⁻¹]

Answer 1

Assuming no heat is lost to the surroundings, the heat lost by hot water when it cools from 100°C to 0°C:

Q = mcΔT

= 100 × 4.2 × 100

= 42000 J

Heat needed to melt all the ice:

Q = mL

= 1000 × 336

= 336000 J

Since 42000 J < 336000 J, only part of the ice melts.

Hence, the final temperature is 0°C.

Mass of ice melted $$(m) = \frac{42000}{336}$$

= 125 g

Ice left unmelted: 1000 − 125 = 875 g

Therefore, 875 g of ice does not melt and the final temperature is 0°C.