A young male adult takes in about 5.0 10-4 m3 of fresh air during a normal breath. fresh air contains approximately 21% oxygen. assuming that the pressure in the lungs is 1.0 105 pa and that air is an ideal gas at a temperature of 310 k, find the number of oxygen molecules in a normal breath.

Question

Frida Lam

Physics

2 February, 09:32

A young male adult takes in about 5.0 10-4 m3 of fresh air during a normal breath. fresh air contains approximately 21% oxygen. assuming that the pressure in the lungs is 1.0 105 pa and that air is an ideal gas at a temperature of 310 k, find the number of oxygen molecules in a normal breath.

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Alfonso Yang · Answer 1

The solution for this problem is:

1 m^3 = (100 cm) ^3 = 1x10^6 cm^3 = 1x10^3 liters

5.0x10^-4 m^3 x 1x10^3 L/m^3 = 5.0x10^-1 L = 0.500 L

1.0x10^5 Pa / 1.01325 Pa per atm = 0.99 atm

n = 0.99 atm x 0.500 L / (0.08206 x 310 K) = 0.0195 moles of gas

N2 = 28 g/mol

O2 = 32 g/mol

100 g air = 21 g O2 or 0.66 moles

100 g air = 79 g N2 or 2.82 moles

0.0194 moles of air; if you assume air is 21 mole % O2, you would get-

0.0194 moles x 0.21 x 6.022x10^23 = 2.45x10^21 O2 molecules