omar asked in Science & MathematicsPhysics · 6 years ago

Physics problem help please. A container in the shape of a cube 11.4 cm on each edge contains air (with equiva?

A container in the shape of a cube 11.4 cm on each edge contains air (with equivalent molar mass 28.9 g/mol) at atmospheric pressure and temperature 295 K.

I need help with this problem and the answer needs to be in kg.

this is my work:

using idal gas law PV=nRT => PV=(m/M)RT => m = (PVM)/(RT)

pressure P=1atm

volume V=11.4 x3 = 34.2 cm3 = 0.0342 L

molar mass M= 28.9 g/mol

gas constant R= 0.08206 (L atm)/(mol K)

temp T=295 K

m = (PVM)/(RT)

m=(1 x 0.0342 x 28.9)/(0.08206 x 295) = 0.0408 g or 0.0000408 kg

wrong answer........ dont know the correct answer or what i am doing wrong.

1 Answer

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  • 6 years ago
    Favorite Answer

    Volume = edge³ (not edge×3) = (11.4cm)³ = 1,481.544 cm³

    As I recall 1 mole ≈ 22.4 liters

    1,481.5cm³/22,400cm³ = .06614 moles

    .06614 moles × 28.9g/mole = 1.9114 g = .0019kg

    Check: Air at STP has density 1.225 kg/m³

    .001481544m³×1.225kg/m³ = .00181kg

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