Question

100 g of ice at −10°C is heated on a gas stove till it forms water at 80°C. Calculate:

1. Heat energy required to bring the ice to 0°C.
2. Heat energy required to melt the ice.
3. Heat energy required to bring water to 80°C.

[sp. heat capacity of ice = 2 Jg⁻¹°C⁻¹; sp. heat capacity of water = 4.2 Jg⁻¹°C⁻¹ and sp. latent heat of fusion of ice is 336 Jg⁻¹]

Answer 1

Given: m = 100 g, c_ice = 2 Jg⁻¹°C⁻¹, c_water = 4.2 Jg⁻¹°C⁻¹, L = 336 Jg⁻¹

(a) Heat to warm ice from −10°C to 0°C:

Δθ = 0 − (−10) = 10°C

H = mcΔθ

= 100 × 2 × 10

= 2000 J

(b) Heat to melt ice at 0°C:

H = mL

= 100 × 336

= 33600 J

(c) Heat to warm water from 0°C to 80°C:

Δθ = 80 − 0 = 80°C

H = mcΔθ

= 100 × 4.2 × 80

=33600 J