Question

Water’s heat of vaporization is 2,257 joules/gram. How much energy is released when 11.2 grams of water vapor condenses into liquid?
A.
202 J
B.
2,246 J
C.
3,840 J
D.
9,950 J
E.
25,300 J

Answer 1

Heat of vaporization is the heat required to vaporize unit mass of a substance at it's boiling point. The heat of vaporization or condensation of water is 2257 J/g.

It means that 1 g of water involves 2257 J energy during condensation or vaporization at its boiling point (100 C)

Given mass of water vapor that is condensing = 11.2 g

Calculating the heat released when 11.2 g of water vapor condenses in to liquid water at 100$^{0}C$:

$11.2 g *2257\frac{J}{g} = 25,278 J$

Rounding the final answer 25,278 J to three significant figures we get, 25,300 J

Therefore the correct answer is E.  25,300 J