Dalton’s Law Vocab /Formulas

Dalton’s Law of Partial Pressures formula

Pa + Pb + Pn= PT

Mole fraction

Xb= Moles gas/moles total= partial pressure gas/pressure total

Collecting gas over water

Reactions that form gases are collected by bubbling the gas into a container of water. The volume displaced is equal to the volume of the gas. A portion of the gas collected water vapor and not the “dry gas.”

Water pressure varies

By temperature of the water.

Two versions of Dalton’s Law to use when calculating the partial pressure of the dry gas

PT (air pressure) = PH2O (water vapor pressure) + P dry gas

PT-PH2O= P dry gas

Diffusion

Movement of gas molecules from an area of high concentration to low concentration.

Effusion

Diffusion of a gas through a small hole.

Graham’s Law of Effusion

Molecules that are lighter will travel faster, than molecules that are heavier.

Lighter gases have a

Faster rate of effusion.

Heavier gases have a

Slower rate of effusion.

Dalton’s Law states that

The total pressure exerted by the mixture of non-reactive gases is equal to the sum of the partial pressures of individual gases.