Question

calculate the density of nitrogen gas molar mass n2 28.0g/mol r=0.0821

Answer 1

Ans. Let the conditions be at RTP (1 atm, 25.0⁰C)

Using Ideal gas equation:    PV = nRT     

            Where, P = pressure in atm

            V = volume in L                   

            n = number of moles

            R = universal gas constant= 0.0821 atm L mol^-1K^-1

            T = absolute temperature (in K) = (⁰C + 273.15) K

# Putting the values in ideal gas equation-

            1.00 atm x V L = 1.0 mol x 0.0821 atm L mol^-1K^-1 x 298.15 K

            Or, V = 24.478115 atm L / 1.00 atm

            Hence, V = 24.478115

Therefore, volume of 1 mol N₂ gas (assumed to behave as ideal gas) = 24.478115 L

# We have, MW of N₂ = 28.0 g mol^-1

So, mass of 1 mol N₂ gas = 28.0 g

Now,

            Density = Mass of 1 mol gas / Volume of 1 mol gas

                                    = 28.0 g / 24.478115 L

                                    = 1.14388 g/ L

Therefore, density of N₂ gas at RTP = 1.14388 g/ L

Note: Density of gas is greatly affected by temperature. So, if you want to calculate density at any other temperature, follow the steps as explained above.