Question

• A steel cylinder with a volume of 15.0 L is filled with 84.9 g of nitrogen gas at 25°C. Calculate the pressure (in atm) of the N2 gas in the cylinder.

Answer 1

Given

Volume = 15 L

Mass of nitrogen= 84.9 g

Temperature= 25°C = (25+273) K = 298 K

Using ideal gas equation

PV = nRT

==>

P = nRT/V

R is universal gas constant = 0.08206 L atm/mol K

n is the no of moles

No of moles= mass/ molar mass

Molar mass of nitrogen gas(N2) = 28 g/mol

So

No of moles= 84.9 g/28 g/mol

= 3.03 moles

Now

P = (3.03 moles)*(0.08206 L atm/mol K)(298 K)/15 L

= 4.94 atm