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An unknown gas shows a density of 2.4 gram per liter at 273^0 C and 1140 mm Hg pressure. What is the gram molecular mass of this gas?

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shedrick333 eNotes educator | Certified Educator

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There is a calculator at http://easycalculation.com/chemistry/molar-mass-ofgas.php that may help you.

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mwmovr40 eNotes educator | Certified Educator

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From the Ideal Gas Law we get

PV = nRT, where P is pressure, V is volume, n is number of moels, R is the Ideal Gas Constant, and T is the temperature in Kelvin.

Solving for n, we get the number of moles of gas (remembering to convert the pressure to ATM, and temperature to Kelvins).

n = PV/RT

n = 1.5ATM*1L/(0.0821 LATM/molK)(546K)

n = 0.033 moles.

molar mass = mass/moles = 2.4g/0.033mole = 72.7 g/mole

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