Question

How much heat is required to turn 1.5 kg of water at a temperature of 5°C into 1.5 kg of water vapour at 150°C? (to 2 s.f and in MJ)

[c_water = 4190 J kg⁻¹ K⁻¹, c_water-vapour = 2010 J kg⁻¹ K⁻¹, L_vap-water = 2256×10³ J kg⁻¹]

Answer 1

$Q=1.5\times(4190\times95+2010+2256\times10^{3}\times50)=18027690 \ J = 18 \ MJ.$

Answer: Q = 18 MJ.