test 3

• daltons law of partial pressure: total pressure of a mixture of gases is the sum of the partial pressure of each gas
• postulate of kinetic molecular theory: volume of individual gas particles are negligible (so small they don't matter)
• postulate of kinetic molecular theory: particles of gas are in constant motion so collision of gas particles with walls of container causes pressure
• postulate of kinetic molecular theory: particles of gasses don't attract or repel each other
• postulate of kinetic molecular theory: average kinetic energy of a gas is directly proportional to the temperature (only in Kelvin)
• root mean squared velocity is a special average of the velocities of gas; it keeps opposite velocities from canceling out
• the M in the root mean squared velocity equation is the mass in kilograms of a mole of the gas (molar mass)
• bigger molar mass = slower velocity and smaller molar mass = faster velocity
• effusion is the movement of gas molecules from one container to another through a tiny hole
• grahams law shows the ratio of the rate of effusion between two gasses of different molar masses
• diffusion is the mixing of gases
• diffusion is much more theoretically complicated because many gases may be present and collide with the gas that is diffusing
• biggest deviations from ideal behavior are low temperature and high pressure
• PV/nRT = 1 for ideal gases
• the "b" van der waals correction corrects for volume of molecules
• the "a" van der waals correction corrects for attraction of molecules (pressure)
• larger a & b values = bigger deviations from ideal behavior
• a gas with a smaller b value will take up the most volume
• SI unit for energy: Joule (J)
• Pext = external pressure
• when volume expands energy is leaving the system so work is negative
• conceptually you can tell P-V work has happened when there's been a change in the amount of gas caused by a chemical reaction
• visually you can tell P-V work has happened when the piston moves up in a diagram
• change in internal energy of a system (U) is zero for an isolated system
• system can exchange internal energy with its surroundings through heat (q) or work (w)
• change in internal energy (ΔU) = heat (q) + work (w)
• when a system releases heat into its surroundings heat (q) and work (w) are negative
• the amount of heat (q) needed to change the temperature of a substance depends on how much temperature changes, quantity of substance, and the nature of the substance
• SI unit for heat is Joule (J)
• 1 calorie (cal) is the quantity needed to change the temperature of 1 gram of water by 1 degrees Celsius
• 1 calorie = 4.184 J
• any property that has unique value for a specific state is a function of state
• functions of state do not depend on how that state was established (path independent)
• heat and work are functions that depend on the path taken when a system undergoes a change
• heat capacity (C) = q/ΔT
• molar heat capacity = nCΔT
• specific heat capacity = mCΔT (m = mass)
• q is positive if heat is gained and negative if heat is lost
• heat gained by the system is lost by the surroundings
• experimental determination of specific heat: heat transferred from substance 1 to substance 2 will be equal in magnitude and have opposite signs