#"NTP"# is #"20"^@"C"# or #"293.15 K"# (used for gas laws), and #"1 atm"#.

Use the equation for the ideal gas law, and solve for moles #(n)#. Once you have moles, you can calculate the mass of nitrogen gas #("N"_2)# by multiplying the moles by its molar mass.

#PV=nRT#,

where #P# is pressure, #V# is volume, #n# is moles, #R# is the gas constant (varies with units used), and #T# is temperature in Kelvins.

**Organize data:**

**Known**

#P="1 atm"#

#V="22.4 L"#

#R="0.082057338 L atm K"^(−1) "mol"^(−1)"#

https://en.wikipedia.org/wiki/Gas_constant

#T="293.15 K"#

#"Molar mass of nitrogen gas (N"_2)"##=##"28.014 g/mol"#

**Unknown**

#n#

**Determining moles #"N"_2#**

Rearrange the ideal gas law equation to isolate #n#. Plug in the known values and solve.

#n=(PV)/(RT)#

#"nN"_2=((1color(red)cancel(color(black)("atm"))xx22.4color(red)cancel(color(black)("L"))))/((0.082057338 color(red)cancel(color(black)("L")) color(red)cancel(color(black)("atm")) color(red)cancel(color(black)("K"))^(−1) "mol"^(−1)""xx293.15color(red)cancel(color(black)("K"))))="0.931 mol N"_2"#

**Mass (weight) of #"N"_2#**

#0.931color(red)cancel(color(black)("mol N"_2))xx(28.014"g N"_2)/(1color(red)cancel(color(black)("mol N"_2)))="26.1 g N"_2"#