a flask of 0.30 L was weighted after it had been evacuated. It was then filled with a gas of unknown molecular mass at 760 mm of Hg and temperature of 300 K. The increase in mass of flask was found to be 0.997 g. Determine the molecular mass

The molecular mass : 81.72 g/mol

In general, the gas equation can be written  

where  

P = pressure, atm , N/m²

V = volume, liter  

n = number of moles  

R = gas constant = 0.082 l.atm / mol K (P= atm, v= liter),or 8,314 J/mol K (P=Pa or N/m2, v= m³)

T = temperature, Kelvin  

P = 760 mmHg=1 atm

T = 300 K

V = 0.3 L

Number of moles :

The molecular mass (MW) :

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