Chemistry · Gases. The idea in plain words, the rules to remember, the mistake to avoid and a worked example, written and checked by Mega Lecture.
In a mixture of gases that do not react, each gas behaves as if it were alone in the vessel. The pressure it exerts is its partial pressure, and the partial pressures add up to the total pressure. This is Dalton's law.
Gases spread out and mix by diffusion, and escape through a tiny hole by effusion. Graham's law says lighter gases do both faster.
The kinetic molecular theory explains these laws. It pictures a gas as very small molecules, far apart, moving randomly in straight lines and hitting each other and the walls. Their average kinetic energy depends only on the absolute temperature.
In Graham's law students put the molar masses the same way up as the rates. The ratio is inverted: the gas with the smaller molar mass has the larger rate.
Answer: 0.5 atm. Hydrogen exerts the other 1.5 atm, although its mass is smaller.
Type what you are stuck on. The helper finds the explanation, worked examples and the notes to read, free and instant.
← Gas laws and the ideal gas equationNon-ideal behaviour, liquefaction and plasma →Take a Chemistry test