Answer:
q= 395.6 kJ
w= 30.1429 kJ
ΔE= 365.4571 kJ
ΔH= 395.6 kJ
Explanation:
First law of thermodynamics:
ΔE = q - w
(q is taken positive when enters to the system and w is taken positive when it is applied to the surroundings)
number of moles = mass / molar mass = 175/18 = 9.72 mol of water
ΔH = number of moles * heat of vaporization = 9.72*40.7 = 395.6 kJ
At constant pressure:
q = ΔH = 395.6 kJ
When water evaporates, it is expanded, then the work is made on the surroundings. At constant pressure:
W = n*R*T
where n is the number of moles, R is the gas constant (8.314 J/(mol*K)) and T is the temperature (in K)
W = 9.72*8.314*(273 + 100) = 30142.9 J = 30.1429 kJ
Finally:
ΔE = q - w = 395.6 - 30.1429 = 365.4571 kJ
