Question

A child's lungs can hold 2.20 L. How many grams of air do her lungs hold at a pressure of 102 kPa and a body temperature of 37°C?

Answer 1

Answer:

2.5 x g

The ideal gas equation gives us:

PV = n RT

P is the pressure

V is the volume

R is the gas constant

8.31 x J/K/mol

T is the absolute temperature

n is the number of moles

n= PVRT

Converting

L to m3

and deg C to K gives:

n = 102 × 103 × 2.20 × 10 − 38.31 × 310 = 0.087 x mol

Since we are told that 1 mole weighs 29g then the mass of air is given by:

m = 0.0871 × 29 = 2.5 lg to 2 sig fig.

The Ideal Gas Equation applies to a closed system and the lungs are not a closed system. Lets assume that at 2.20 L the child hold its breath (though not for too long).

Explanation: