Calculate the change in entropy that occurs in the system when 48.6 g of water (h2o) vaporizes from a liquid to a gas at its boiling point (100.0 ∘c). the heat of vaporization is 40.7 kj/mol.

The water is vaporizing at 100°C. The vaporizing water is the system to be studied. Given the mass of water is 48.6 g. The chemical formula of water is H₂O. The molar mass of water is 18 g/ mol
moles of water are:
moles = mass / molar mass = 48.6 / 18 = 2.7 mol
The water is vaporizing, Thus, it gains the heat energy to vaporize
The amount of heat gained by the water is:
Q = n ΔH⁰ vap
   = 2.7 mol x 40.7 kJ/mol x 1000J / 1kJ = 109890 J
Q is the amount of heat lost or gained, n is the number of moles of water and ΔH⁰vap is heat of vaporization.
The expression for entropy change is:
ΔS = Q / T = 109890 J / 373 K = 294.6 J/K
The change in the entropy of the system to three significant digits is 295 J/K

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