Problem: A sample of air contains 78.08% nitrogen, 20.94% oxygen, 0.05% carbon dioxide, and 0.93% argon, by volume. How many molecules of each gas are present in 1.00 L of the sample at 25°C and 1.00 atm?

FREE Expert Solution

Volume percent:


% volume=volume componenttotal volume×100


For 1.00 L sample: (divide %vol by 100)


  • VN2 = 0.7808(1.00 L) = 0.7808 L N2
  • VO2 = 0.2094(1.00 L) = 0.2094 L O2
  • VCO2 = 0.0005(1.00 L) = 0.0005 L CO2
  • VAr = 0.0093(1.00 L) = 0 0.0093 L Ar


Ideal gas law:


PV=nRTPVRT=nRTRTn=PVRT


T = 25°C  + 273.15 = 298.15 K


Solving for moles of each gas:


nN2=(1.0 atm)(0.7808 L)(0.08206 L·atmmol·K)(298.15 K)= 0.0319 mol

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Problem Details

A sample of air contains 78.08% nitrogen, 20.94% oxygen, 0.05% carbon dioxide, and 0.93% argon, by volume. How many molecules of each gas are present in 1.00 L of the sample at 25°C and 1.00 atm?

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What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the Mole Fraction concept. You can view video lessons to learn Mole Fraction. Or if you need more Mole Fraction practice, you can also practice Mole Fraction practice problems.

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Based on our data, we think this problem is relevant for Professor Artun's class at DEANZA.

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Our data indicates that this problem or a close variation was asked in Chemistry: The Molecular Nature of Matter and Change - Silberberg 8th Edition. You can also practice Chemistry: The Molecular Nature of Matter and Change - Silberberg 8th Edition practice problems.