Question

Suppose during volleyball practice, you lost 2.0 lbs of water due to sweating. If all of this water evaporated, how much energy did the water absorb from your body? Express your answer in kJ.  2.2 lbs = 1.0 kg

Answer 1

Given

2.2 lbs = 1.0 Kg

2.0 lbs = $\frac{1.0}{2.2}$ x 2.0 = 0.91 kg = 910 g

Q = n x ΔH

Q = heat gained

n = no. of moles = $\frac{Given.mass}{molecular.mass}$

n = no. of moles = $\frac{910g}{180g/mol}$ = 50.55 moles

ΔH = enthalpy of vaporization of water

ΔH = 40.65 KJ/moles

Q = n x ΔH

Q = 50.55 moles x 40.65 KJ/moles

Q = 2054.86 KJ