Answer:
Enthalpy change = 74.36 kJ
Explanation:
Enthalpy change is defines as the heat absorbed or evolved during a chemical reaction at constant pressure and volume
Reaction:
H2O(l) --> H2O(g)
DHr = mCsDT
Where m is the mass of water
Cs is the specific heat capacity
DT is the temperature difference
= 31.6 * 4.18 * (25 - 3.2)
= 2879.518 J
DHvap = 44kJ/mol
Moles of water = mass/molecular weight
Molecular weight = (1*2) + 16
= 18g/mol
Moles of water = 31.6/18
= 1.756 moles
DHvap = 44 * 1.756
= 77.244kJ
DH = DHproduct - DHreactant
DHproduct = DHvap = 77.24kJ
DHreactant = DHr = 2879.518J = 2.880kJ
= 77.24 - 2.880
DH = 74.36kJ
Enthalpy change = 74.36 kJ
