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) :

explanation: it gains negative electrons, therefore becoming negatively charged. as charge cannot be created, nor destroyed, only transferred, this leaves the wool positive. now that they have opposite charges, the two items attract.