# The composition of dry air is approximately 78% nitrogen, 21% oxygen, and 1% other gases. What is the partial pressure of nitrogen at standard atmospheric pressure (101.3 kPa)?

$79.0335 k P a$
According to Dalton's law of partial pressures, the partial pressure of a gas is equal to the mole fraction of the gas multiplied by the total pressure. Thus, the partial pressure of ${N}_{2}$ (in $k P a$)is
${P}_{{N}_{2}} = \left(0.78\right) \left(101.325 k P a\right) = 79.0335 k P a$