The Behavior of Gases

Factors Affecting Gas Pressure Amount of Gas – Adding gas increases gas particles, increases collisions, and therefore increases pressure Volume – Decreasing the volume of the container increases the number of collisions and raises the pressure Temperature – Raising the temperature of a gas causes the particles to move faster and run into each other more often

Boyle’s Law Pressure-Volume Relationship For a given mass of gas at constant temperature, the volume of the gas varies inversely with pressure Decrease volume/Increase pressure Increase volume/Decrease pressure P1 V1 = P2 V2

Charles’s Law Temperature-Volume Relationship The volume of a mixed mass of a gas is directly proportional to its Kelvin temperature if the pressure is kept constant Increase temperature/Increase volume Decrease temperature/Decrease volume V1 V2 T1 T2 =

Gay-Lussac’s Temperature-Pressure Relationship Pressure of a gas is directly proportional to the Kelvin temperature if the volume remains constant P1 P2 T1 T2 =

Combined Gas Law Single expression that combines the three gas laws P1 V1 P2 V2 T1 T2 =

Ideal Gas Law R or P V = nRT Equation that expresses how much gas is in a system Moles of gas (n) Ideal gas constant (R) = 8.31 P V T n R = or P V = nRT

Partial Pressure of Gas At constant volume and temperature, the total pressure exerted by a mixture of gases is equal to the sum of the partial pressure of the component of gas Ptotal = P1 + P2 + P3 + ………..

Graham’s Law Diffusion – the tendency of molecules to move toward areas of lower concentration Effusion – the process in which gas escapes through a tiny hole in its container Graham’s Law – the rate of effusion of a gas is inversely proportional to the square root of the gas’s molar mass RateA Molar massB RateB Molar massA =