Question

How much heat is evolved in converting 1.00 mol of steam at 140.0 ?C to ice at -45.0 ?C? The heat capacity of steam is 2.01 J/(g??C) and of ice is 2.09 J/(g??C).

Answer 1

The chemical formula for steam is H2O(g)

mass of steam = mole of steam * molar mass of H2O
= 1 * (1*2+16) = 18 g

by E = m * c * change in temperature,
From 140C steam to 100C steam
18 * 2.01 * (140-100) = 1447.2J

latent heat of vaporization of water = 2.26x10^6 J/kg* 0.018 = 40680 J

From 100C water to 0C water
18 * 4.2 * (100-0) = 7560 J

latent heat of fusion of ice = 334 J/g * 18 g = 6012 J

From 0C ice to -45C ice
18 * 2.09 * (45-0)
= 1692.9 J

1447.2 + 40680 + 7560 + 6012 + 1692.9 = 57392.1 J