Gases KMT = particles constant motion AKE, temperature, pressure, volume, amount of a gas are all related

Pressure & Force D/t collisions of molecules on surfaces P = defined as the force per unit area on a surface = force/area Force unit = newton (N)

The Barometer Pressure depends on area of contact; smaller area, greater pressure Ex.: high heels; ballerina Atmosphere exerts pressure - total of individual gas pressures (mostly N, then O) Measured using barometers Units (ie. 1 torr = 1 mm Hg)

Dalton’s Law of Partial Pressures Partial pressures are exerted by individual gases Law states that total pressure of a gas mixture is the sum of the component pressures P T = P 1 +P 2 +P 3 …

Boyle’s Law Inversely relates pressure and volume Examples? P 1 V 1 =P 2 V 2 What is the constant?

MUST KNOW Use the temperature in Kelvins when solving these gas problems. K = ºC STP means standard temperature (0ºC) pressure (1 atm). 1 atm = kPa = 760 torr = 760 mm Hg

Charles’s Law Directly relates volume and temperature V 1 /T 1 = V 2 /T 2 What is the constant? K = degrees C + 273

Gay-Lussac’s Law Directly relates pressure and temperature P 1 /T 1 =P 2 /T 2 Constant?

Combined Gas Law

Avogadro’s Law Equal volumes of gases at the same temperature and pressure contain equal numbers of molecules. Example: At the same temperature and pressure, balloons of equal volume have equal numbers of molecules, regardless of which gas they contain.

Molar Volume of a Gas 22.4 L at STP STP = 1 atm and 0 degrees C (273 K)

Ideal Gas Law Solve for moles within a gas PV = nRT R is a constant ( L x atm/mol x K). This is used when the volume is in liters, the pressure is in atmospheres, and the temperature is in Kelvins. n is the number of moles Use a table for values of R when other units for n, P, V, and T are used.

Comparison of Diffusion with Effusion Effusion is the process by which gas molecules under pressure pass through a tiny opening. Diffusion is the mixing of two gases by random molecular motion.

Graham’s Law of Effusion Rates of effusion of gases at the same temperature and pressure is inversely proportional to the square roots of their molar masses Square root of Molar Mass B/Square root of Molar Mass A