Dalton's Law and Ideal Gas Law Notes

Calculating Partial Pressure

• The partial pressure of a gas (e.g., oxygen, $O<em>2$) can be calculated as: $Partial Pressure</em>{O<em>2} = \frac{Pressure</em>{exerted \ by \ O_2}}{Total \ Pressure}$

• In a mixture, the total pressure is the sum of individual gas pressures.
  

$P<em>{total} = P</em>{O<em>2} + P</em>{N<em>2} + P</em>{Ar} + P<em>{H</em>2O} + …$

Calculating Percentage of Total Pressure

• To find the percentage of the total pressure exerted by a gas:
  

$Percentage = \frac{Partial \ Pressure \ of \ Gas}{Total \ Pressure} \times 100$

• Example for oxygen:
  

$Percentage \ of \ O_2 = \frac{20.9 \ kPa}{101.3 \ kPa} \approx 0.2063 \approx 20.63 \%$

• This calculation can be done for each gas in the mixture.