Question

Beginning at 20°C, what amount of heat is required to heat 0.3 kg of aluminium to its melting point and then to convert it to liquid? [Specific heat capacity of aluminium = 900 J kg⁻¹ °C⁻¹; specific latent heat of aluminium = 321,000 J kg⁻¹ and melting point of aluminium = 660°C].

Answer 1

Given:

m = 0.3 kg, T₁ ​= 20°C, T₂ ​= 660°C

c = 900 J kg⁻¹ °C⁻¹, L = 321000 J kg⁻¹

Heat required to raise the temperature:

Q₁​ = mcΔT

= 0.3 × 900 × (660 − 20)

= 172800 J

Heat required to melt aluminium:

Q₂ ​= mL

= 0.3 × 321000

= 96300 J

Total heat required:

Q = 172800 + 96300 Q

= 269100 J