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Chaz
Chaz asked in Science & MathematicsChemistry · 9 years ago

Calculate the molar mass of a gaseous substance if 0.125 g of the gas occupies 93.3 mL at STP?

Confused with this chemistry question. Thanks to all those that answer.

2 Answers

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  • Philippe
    Lv 7
    9 years ago
    Favorite Answer

    Hi Chaz,

    P x V = n x R x T

    n = m / M

    . . . therefore :

    P x V = m x R x T / M

    . . . finally :

    M = m x R x T / (P x V)

    M = 0,125 x 8,314 x 273,15 / (101325 x 93,3•10^-6)

    M = 30,0 g/mol

  • a2gal
    Lv 7
    9 years ago

    STP is 1 atm of pressure and 293 K. plug into PV= nRT and solve for n:

    1 atm (0.0933 L) = n (0.0821 L atm/mol K) (273 K)

    0.00416 mol = n

    find molar mass by dividing grams by moles:

    0.125 g/0.00416 mol = 30.03 g/mol

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