Question

2 kg of water at 100°C is contained in a vessel of negligible heat capacity. Into this water is added 3 kg of ice at 0°C. Calculate the amount of water at 0°C at the end of the experiment.

[Take SHC of water = 4.2 × 10³ J kg⁻¹°C⁻¹ and SLH of ice = 336 × 10³ J kg⁻¹]

Answer 1

The heat given out by the hot water as it cools to 0°C:

Q = mcΔT

= 2 × 4.2 × 10³ × 100

= 840000 J

Mass of melted ice $$(m) = \frac{Q}{L}$$

$$= \frac{840000}{336 \times 10^3}$$

= 2.5 kg

Total mass (m) =  Mass of original water + Mass of melted ice

= 2 + 2.5

= 4.5 kg