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Chapter 12 – The Behavior of Gases Test Topics Chapter 12 Test Thursday, April 28th Kinetic Molecular Theory o Principles of the kinetic molecular theory o Kinetic energy (KE) = ½ mass x velocity2, (KE = ½ mv2) understand how particles of different masses differ in their velocities if they have the same kinetic energy (if kinetic energies are equal the particle with the smaller mass must have a higher velocity) o Relationship between kinetic energy and Kelvin temperature (directly proportional, remember this is for Kelvin temp, not just temp in general!) o Factors Affecting Gas Pressure – amount of a gas – as amount of gas increases, pressure also increases volume – as volume as increases, pressure decreases temperature – as temp. increases, pressure also increases Pressure Conversions - (1 atm = 760 mm Hg = 101.3 kPa = 760 torr = 29.92 in. Hg and 1kPa = 1000 Pa) Temperature Conversions (K = oC + 273) All temperatures must be in Kelvin before putting them into any equation! Volume Conversions ( 1 L = 1000 mL) Grams and moles conversions (you will be given a Periodic Table) – grams to moles (1 mol / molar mass) and moles to grams (molar mass / 1 mol) The Gas Laws – you must know the relationship between each variable in these laws. Also, what would a graph of each of these gas laws looks like and be able to identify by name. o Boyle’s (P1V1 = P2V2); pressure and volume are inversely proportional when Kelvin temperature and amount of gas are constant o Charles’ (V1/T1 = V2/T2); volume and Kelvin temperature are directly proportional when pressure and amount of gas are constant o Gay-Lussac’s (P1/T1 = P2/T2 ); pressure and Kelvin temperature are directly proportional when volume and amount of gas are constant o Avogadro’s (V1/n1 = V2/n2); volume and number of moles of gas are directly proportional when pressure and Kelvin temperature are constant Combined Gas Law (P1V1/T1 = P2V2/T2) Ideal Gas Law (PV = nRT); P = pressure in atm or kPa, V = volume in Liters, n = number of moles in moles, and T = Kelvin temperature o Ideal gas constant values (R = 0.0821 L atm/K mol or 8.314 L kPa/K mol) Dalton’s Law of Partial Pressures (PTotal = P1 + P2 + …) o Gases Collected Over Water – you will be given a chart with water vapor pressures; any time a gas is collected over water, the water vapor pressure must be added to the other gas that is collected to determine the total pressure of the mixture of gases. o Including problems with ideal gas law (will have grams or moles) and combined gas laws (no mention of grams or moles anywhere in the problem) Graham’s Law of Effusion – o Diffusion – gas moves from area of higher concentration to area of lower concentration o Effusion – process of a gas escaping or moving through a small hole in a container o Equation for diffusion and effusion problems (Rate 2/ Rate 1) = √(molar mass 1/molar mass 2) Rates must be an amount of gas divided by a period of time (1 mol of gas/25 seconds) not just an amount of time. Rate is inversely proportional to the square root of the molar mass; the higher the molar mass, the lower the rate of effusion and diffusion Stoichiometry with gas laws – usually ideal gas law problems