Question

For a constant pressure of 10^5 Pa, determine the amount of heat needed for the process of taking 2.5 mol h2o from solid state at 0 C to its vapor state at 100 C.

Answer 1

Solution :-

moles of water = 2.5 mol

total amount of heat needed is the sum of the delta H fusion + heat absorbed by liquid state to change from 0 to 100 C and then heat of vaporization

q total = Delta H fus + q water + heat of vap

            = (2.5 mol * 6.1k J/mol)+(2.5 mol * 0.0754 kJ per mol * 100 C ) +(40.6 kJ per mol * 2.5 mol )

            = 135.6 kJ

so the total amount of heat needed is 135.6 kJ or we can round it to 136 kJ