Your lungs hold 4.2 L of air at a temperature of 27°C and a pressure of 101.3 kPa.How many moles of air do your lungs hold? (R = 8.31 J/mol ∙ K)
A)0.15 moles
B)0.17 moles
C)0.19 moles
D)0.21 moles
E)0.23 moles

Question

Quizplus · Accepted Answer

We can use the Ideal Gas Law to solve for the number of moles of air:
PV = nRT
n = PV/RT
n = (101.3 kPa)(4.2 L)/(8.31 J/mol ∙ K)(300 K)
n = 0.169 mol
Rounding to two significant figures gives us 0.17 moles, which is answer choice B.

Your Lungs Hold 4