Question

500 g of water at 60°C is contained in a vessel of negligible heat capacity. Into this water is added 400 g of ice at 0°C. Calculate the amount of ice which does not melt.

[Take SHC of water = 4.2 J g⁻¹°C⁻¹ and S.L.H. of ice = 336 J g⁻¹]

Answer 1

Heat given out by the water as it cools to 0°C is:

Q = mcΔT

= 500 × 4.2 × 60

= 126000 J

The mass of ice that melts is:

$$m = \frac{Q}{L}$$

$$= \frac{126000}{336}$$

= 375 g

Therefore, the ice that does not melt is 400 − 375 = 25 g.