# Gases in GChem

krabi's version from 2015-07-15 22:50

## Section

What is a key property of gases? They have no fixed volume, they are compressible and will fill all compressible space.
What are the most important properties of KMT? How pressure, volume and temperature interact.
1) What are the three assumptions of KMT?Small molecules take up no volume
2) What are the three assumptions of KMT?The pressure results in elastic collisions against the container walls; gas molecules are in constant motion, moving in straight lines and at random directions between all collisions
3) What are the three assumptions of KMT?Molecules run around at different speeds, and their kinetic energy is linked to their temperature
What is an ideal gas?Satifies all three ideas of KMT - most real gases act like ideals
What is the key unit for volume?1 cm3 = 1 cc = 1 mL & 1 m3 = 1000L
What does the ideal gas law claim?PV = nRT
What are standard temperature and pressure conditions?1 atm & 273 K
What do molecules of an ideal gas do?They take up no volume and actually experience no intermolecular forces
How do Real Gases act?Usually they act like idea gases, BUT - act naughty and move away from ideal in cold temperatures and under high pressure
What does Dalton Law state?The overall pressure of gases = the sum of each individual partial pressure
What does the total pressure of gases equal?Total pressure of all gases are equal to its mole fraction within the gas mix
What does the temperature measure?Measure the average kinetic energy of molecules within a sample
What is the Grahamâ€™s law of Effusion?The effusion of a gas is inverse proportion to its molecular weight. E.g. lighter gases effuse faster than heavy gases (just like people).
How do you calculate Kelvin?C + 273.15
What is the absolute temperature scale (K)?All gases would theoretically get a Zero value (when pressure lowers to a perfect vacuum). Used in all gas law equations.
What is atmospheric pressure at sea level?101.3 kPa = 1 atm = 760 torr = 760 mm Hg
What is the universal gas constant?R = 0.0821
What is Charles Law?If the pressure is constant, volume is linked to temperature V~T
What happens to gas (when pressure is constant)?Gas expands when heated, contracts when it cools down
What happens to pressure (when temp stays constant)?Pressure is inverse proportional to volume (with = temps)
What is Boyles Law?If volume decreases, pressure increases and vice versa
If volume is constant, what happens to pressure and temp?Pressure is linked proportionally to temperature.
What is the combined Gas Law equation?PV/T = PV/T, 1 = 2 (Only when n stays constant!)
How can you determine standard molar volume?V = nRT/P
What is the equation for Gragamâ€™s Law of Effusion?Rate of Effusion Gas A/Rate of Effusion Gas B = [sq.rt] Molar Mass Gas B/Molar Mass of Gas A