Problem: Olympic cyclists fill their tires with helium to make them lighter. Assume that the volume of the tire is 860 mL , that it is filled to a total pressure of 125 psi , and that the temperature is 25 oC. Also, assume an average molar mass for air of 28.8 g/mol.What is the mass difference between the two?

FREE Expert Solution

Calculate the moles of that can occupy the tire:

PV=nRTPVRT=nRTRTn=PVRT


T = 25°C +273.15 = 298.15 K

V=860 mL×10-3 L1 mL

V = 0.860 L


P=125 psi×1 atm14.6959 psi

P = 8.6058 atm


n=(8.6058 atm)(0.860 L)(0.08206L·atmmol·K)(298.15 K)

n = 0.299 mol ≈ 0.30 mol


Calculate the mass of helium (He) and air:

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Problem Details

Olympic cyclists fill their tires with helium to make them lighter. Assume that the volume of the tire is 860 mL , that it is filled to a total pressure of 125 psi , and that the temperature is 25 oC. Also, assume an average molar mass for air of 28.8 g/mol.

What is the mass difference between the two?

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