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A 1.49 g sample of a pure gas occupies a volume of 981 mL at 42 degrees celcius and 878...

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bahadur | Student, Undergraduate | (Level 3) eNoter

Posted June 8, 2013 at 4:44 PM via web

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A 1.49 g sample of a pure gas occupies a volume of 981 mL at 42 degrees celcius and 878 mm Hg. Determine the molar mass of the compound.

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jeew-m | College Teacher | (Level 1) Educator Emeritus

Posted June 9, 2013 at 2:41 AM (Answer #2)

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Using the ideal gas equation;

`PV = nRT`

`n = (PV)/(RT)`

 

`P = 878mmHg = 878/760 atm = 1.155atm`

`V = 981mL = 0.981L`

`R = 0.08206(atmL/)(molK)`

`T = 273+42 = 315K`

 

`n = (1.155xx0.981)/(0.8206xx315)`

`n = 0.0044 mol`

 

`n = m/M`

`0.004 = 1.49/M`

`M = 1.49/0.004 = 338.64g/(mol)`

 

So the molar mass of the compound is 338.64g/mol

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