AP Chem: Gases (Ideal, KMT, and Non-Ideal)

Pressure

Pressure

the amount of force exerted per unit area of a surface

Gas pressure

the force that the gas exerts on its container based on how hard it hits the container and how often

volume

the region of space that the gas occupies

number of moles

number of gas particles

ideal gas law constant

relates the four other variables together

temperature (use Kelvin)

average kinetic energy of a gas

inversely proportional

Effect of volume on pressure; as volume decreases, pressure increases and the greater concentration of particles result in greater frequency of collisions

directly proportional

effect of number of moles on pressure; as the number of moles increases the number of collisions increases

directly proportional

effect of temperature on pressure

as the average kinetic energy of the molecules increases, the P increases as the number of collisions occur more often and are more energetic

partial pressure

the pressure of each gas in a mixture based on the amount of gas particles

mole fraction

Xi=ni/ntotal

partial pressure/ mole fraction (NO UNITS)

The partial pressure of a gas in a mixture is equal to its mole fraction multiplied by the total pressure.

Xa= moles/ total moles

Xi= Xa x Ptotal

Gas behavior

-particles are in continuous random motion; btwn collisions they have constant velocity and direction; after collisons they have new direction and velocity; elastic collison; Kelvin is proportional to the average kinetic energy

At the same temp

lighter particles move faster; heavier particles move slower when?

negligable bc everyday containers are much larger than the gas particles; 0

In an ideal gas size is what? They have what volume?

constant kinetic energy but diff velocities depending on the MM

Constant temp=

attractions among gas molecules esp close ones; and particle volumes at high pressures

Deviations may occur from?

Ideal Gases and KMT

-elastic collisions

-no attractive or repulsive forces btwn particles

-particle volumes are negligible

-PV-nRT

Real Gas Behavio

-all gases can condense; there are attractive forces

-molecules vary in size and have volume

-PV IS NOT EQUAL TO NRT

strong IMF= low pressure

With significant attractions between particles, the number of collisions and the walls of the collisions decrease and have a low pressure (stick together as one unit and hit the wall as one unit)

effect of IMFS

IMF increaes, the pressure decreases

-high temps the IMFS are negligible and gases behave ideally

-low temps IMFs become significant (Non ideal)

Effect of Molecular Volume

-large volume of particle= less room to move and leads to more collisions; large particles= higher pressure

decreasing volume of container

as the volume of th container becoems smaller the particle volume becomes more significant more than predicted; very small volume= higher pressure