Gas Particle Velocity and Real Gases Flashcards
At a given temperature, how does the average kinetic energy of gas particles differ?
It doesn’t. At a given temperature, gas particles have the same average kinetic energy.
What is the root-mean-square speed (rms)?
The speed of a molecule with the average kinetic energy.
What is the formula for root-mean-square speed?
Urms = √(3RT/MM)
R = gas constant
T = temp (K)
MM = molar mass
Which gas constant is used to find the root-mean-square speed?
8.314 J/(mol)(K)
What are the units of molar mass used to find the root-mean-square speed?
kg/mol
What is diffusion?
The process of molecules spreading from a high concentration to a low concentration
What is effusion?
The process of gas escaping through a small hole in its container.
What does Graham’s Law say?
The rate of gas effusion is inversely proportional to the square root of its molar mass.
Does a lighter or heavier gas effuse faster at a given temperature?
A lighter gas – it has a higher effusion rate
What formula do you use to find the ratio of effusion rates mathematically?
(Rate of unknown gas X)/(Rate of known gas Y) = √[(MM of Y)/(MM of X)
What formula do you use to find the molar mass of unknown gas X from the ratio of effusion rates between it and a known gas Y?
MMx = MMy * [(Rate of Y)/(Rate of X)]^2
What are two ways that gases deviate from KMT?
They have volumes determined by the sizes of their atoms
They have intermolecular forces
Under what conditions do real gases deviate most from ideal gases? Why?
At low temperature and high pressure
Because this is where particles interact the strongest
What qualities of a gas sample affect the speed of its particles?
Temperature (directly) and molar mass (inversely)
Moles and pressure don’t matter
Under what conditions do gases behave most like ideal gases?
High temperature and low pressure
