Question

200 g of ice at 0°C, just melts when a cube of metal of mass 175 g and at 800°C is placed over a block of ice. Calculate the specific latent heat of fusion of ice.

[Specific heat capacity of metal is 0.6 J g⁻¹°C⁻¹]

Answer 1

Heat lost by the metal cube = heat gained by the ice to melt.

For metal:

m = 175 g, c = 0.6 J g⁻¹°C⁻¹, ΔT = 800 − 0 = 800°C 

Heat lost = mcΔT

= 175 × 0.6 × 800

= 84000 J

For ice:

Mass of ice = 200 g, so heat gained = 200 L

200 L = 84000

$$L=\frac{84000}{200}$$

= 420 J g⁻¹

Therefore, the specific latent heat of fusion of ice is 420 J g⁻¹ (or 4.2 × 10⁵ J kg⁻¹).