Question

It has been determined that the body can generate 5500 kJ of energy during one hour of strenuous exercise. Perspiration is the body’s mechanism for eliminating this heat. What mass of water would have to be evaporated through perspiration to rid the body of the heat generated during 2 hours of exercise

Answer 1

4,874 g

Step-by-step explanation:

The body can generate 5,500 kJ during 1 hour of strenuous exercise. The heat generated during 2 hours of exercise is:

2 h × (5,500 kJ/1 h) = 11,000 kJ

This heat is used for the vaporization of water. We can calculate the heat (Q) using the following expression.

Q = ΔH°vap × m

where,

ΔH°vap is the enthalpy of vaporization of water

m is the mass of water

m = Q/ΔH°vap

m = (11,000 × 10³ J) / (2,257 J/g)

m = 4,874 g

Answer 2

There is 4.88 kg of water evaporated.

Step-by-step explanation:

Step 1: Data given

5500 kJ of energy during one hour of strenuous exercise.

Δh = Heat of vaporization of water is 40.6 kJ/mol

Step 2: Calculate the mass of water evaporated

Q = 2* 5500 kJ = 11000 kJ

mass = [( Q ) / ( Δh ) ] [ Molar mass of water]

mass = [ ( 11,000 kj / 40.6 kJ/mol) * 18.02 g/mol )

mass = 4882.27 grams ≈ 4.88 kg of water

There is 4.88 kg of water evaporated.