Yahoo Answers: Answers and Comments for Determine the density of air in grams per liter at a temperature of 20.5 deg. C and a pressure of 755 mmHg? [Chemistry]
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From Anonymous
enUS
Sat, 24 Mar 2012 05:35:06 +0000
3
Yahoo Answers: Answers and Comments for Determine the density of air in grams per liter at a temperature of 20.5 deg. C and a pressure of 755 mmHg? [Chemistry]
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From Robert D: You can use the ideal gas law equation to solv...
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Sat, 24 Mar 2012 06:54:26 +0000
You can use the ideal gas law equation to solve this problem.
pV = nRT
Use R = 0.08206 L*atm/K*mol >> This means you will need to convert T and p to the correct units.
density = mass/volume
apparent molar mass of air = M = 0.20(31.9988 g/mol) + 0.80(28.0134 g/mol)
M = 28.8105 g/mol
Temperature = 20.5°C = 20.5°C + 273.2 = 293.7 K
p = 755 torr(1 atm)/(760.0 torr) = 0.993 atm
V is per L, so use 1.00 L for volume.
(0.993 atm)(1.00 L) = [(mass)/(28.8105 g/mol)][(0.08206 L*atm/K*mol)(293.7 K)
Now simplify: mass = MpV/RT >> This was rearranged to solve for the mass.
mass = (28.8105 g/mol)(0.993 atm)(1.00 L)/(0.08206 L*atm/K*mol)(293.7 K)
mass = 1.19 g
Since the volume used was 1.00 L in the calculation the density is:
D = (1.19 g)/(1.00 L) = 1.19 g/L
Hope this is helpful to you. JIL HIR