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HELP! Volume at STP question, must be done ASAP! PLEASE?

An experiment is conducted in which 0.000535 mol of H2(g) is chemically generated in a closed headspace of volume 119.9 cm3 at 24.0 °C, thereby raising the total pressure by 0.109 atm.

What would be the corresponding volume of that same amount of H2(g) if it were isolated under STP conditions (exactly 0 °C and 1 atm)?

Use this to calculate the molar volume of the gas at STP.

1 Answer

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  • 9 years ago
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    PV=nRT, where P is pressure in atm, V is volume in L, n is the number of moles, R is a constant and T is the temperature in kelvin. Based on the data in the problem, we can determine all but V.

    P = 1 atm

    n = 0.000535 mol

    R = 0.0821 L * atm / (mol * K)

    T = 273 K

    Solve for V in the equation --> V = (nRT) / P

    Plug in the values --> V = [(0.000535 mol)(0.0821 L*atm/(mol*k))(273 K)] / (1 atm) = .01199 L

    Convert L to mL and to cm3 --> 0.01199 L * (1000 mL / L) * (1 cm3 / mL) = 11.99 cm3

    Molar volume as STP is just the liters per mol under standard conditions. So to calculate, just divide the volume in liters by the number of moles.

    M.V. = V / n = (.01199 L / .000535 mol) = 22.4 L

    Which is the volume one mole of any gas occupies under standard conditions.

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