Question

What minimum heat is needed to bring 150 g of water at 20 ∘c to the boiling point and completely boil it away? the specific heat of water is 4190 j/(kg⋅k) and its heat of vaporization is 22.6×105 j/kg?

Answer 1

Try this solution:

if given m=0.15 kg; t₁=20 °C; t₂=100 °C; c=4190 J/(kg*C); q=226*10⁴ J/kg., then

Q=Q₁+Q₂,

where Q₁=cm(t₂-t₁) and Q₂=q*m.

Finally,

Q=cm(t₂-t₁)+qm;

Q=4190*0.15*80+2240000*0.15=386280 J=386.28 kJ.