A person inhales air richer in O2 and exhales air richer in CO2 and water vapor.

Question

A person inhales air richer in O2 and exhales air richer in CO2 and water vapor. During each hour of sleep, a person exhales a total of 300. L of this CO2-enriched and H2O-enriched air. (a) If the partial pressures of CO2 and H2O in exhaled air are each 32.5 torr at 35.0°C, calculate the masses of CO2 and of H2O exhaled in 1.00 hour of sleep. CO2 WebAssign will check your answer for the correct number of significant figures. g H2O WebAssign will check your answer for the correct number of significant figures. g (b) How many grams of body mass does the person lose in about 8 h sleep if all the CO2 and H2O exhaled come from the metabolism of glucose? (Note: 8 h has 1 significant figure, so round your answer to 1 sig. fig.) WebAssign will check your answer for the correct number of significant figures. g C6H12O6(s) + 6 O2(g) 6 CO2(g) + 6 H2O(g)

Explanation / Answer

a)

pressure = 32.5 torr = 0.04276 atm

temperature = 35 oC = 308.15 K

volume = 300 L

P V = n R T

0.04276 x 300 = n x 0.0821 x 308.15

n = 0.50705

moles = 0.50705

mass of CO2 = 0.50705 x 44 = 22.3 g

mass of CO2 = 22.3 g

mass of H2O = 9.14 g

b)

moles of glucose metabolised in 1 h = 0.50705 / 6 = 0.084508 mol

moles of glucose metabolised in 8 h = 0.67607 moles

mass lost = moles of glucose x molecular weight of glucose

               =   0.67607 x 180

               = 121.7 g

mass lose = 100 g

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