Question

(4) while you were "sweating" your chemistry test, water vapor evaporates from your body, absorbing 125 kj of energy. (assume no temperature change). what mass of water evaporates?

Answer 1

The heat absorbed by the water that evaporates from the body is the so called latent vaporization heat of water.

The standard latent vaporization heat of water is 2,264.705 kJ / kg.

So, you just have to divide 125 kJ / 2,264.705 kJ/kg = 0.0552 kg = 55.2 g

Answer: 55.2 g

Answer 2

Answer:

The mass of water evaporated is 55.31 g.

Explanation:

Latent heat of vaporization of water $\Delta H_{vap}= 2260 J/g$

Mass of water evaporated = m

Change in temperature = ΔT = nil

Energy required to to evaporate the m mass of water present in sweat= Q

Q = 125 kJ = 125000 J

$Q=\Delta H_{vap}\times m$

$125000 J=2260 J/g\times m$

$m=\frac{125000 J}{2260 J/g}=55.31 g$

The mass of water evaporated is 55.31 g.