What's in a Unit?
What is the SI unit of pressure?
atm
How does one convert units of temperature reported in °C to K?
Add 273.15.
What law mathematically describes the inversely proportional relationship between volume and pressure?
Boyle's Law
V inversely proportional to 1/P
VP = Constant
What law mathematically describes the total pressure of a gas as the sum of the partial pressures of its individual pressures?
Dalton's Law of Partial Pressure
Ptotal = Pa + Pb + Pc....
In a manometer, a device used to measure the pressure exerted by a trapped gas, the mercury level is measured to be higher on the side open to the atmosphere. Does the trapped gas exert a higher or lower pressure than the atmosphere?
Higher pressure than the atmosphere.
Subtract from total atmospheric pressure.
What does the unit n stand for in gas calculations?
moles
What conversion factor is needed to convert pressure in torr to mm Hg?
1 torr = 1 mm Hg
What law mathematically describes the proportional relationship between volume and temperature?
Charles's Law
V proportional to T
V/T = Constant
How can you determine the total moles of a gas mixture?
Add them all up!
If not in moles, but grams, covert to moles and add them up!
How do you solve PV=nRT for Volume when you measure volume at STP?
Plug in STP.
What is the unit of temperature commonly used in gas calculations?
K
What conversion factor is needed to convert pressure in mm Hg to atm?
760 mm Hg = 1 atm
What law mathematically describes the inversely proportional relationship between volume and amount (moles)?
Avogadro's Law
V proportional to n
V/n = Constant
How do you determine the mole fraction of a gas within a mixture?
Xa = na/ntotal
How do you solve PV=nRT for mass when you have already determine a volume at STP?
Solve for n and convert to grams.
What is the unit of volume commonly used in gas calculations?
L
What is the standard volume of 1 mole of gas?
22.4 L
Can the simple gas law be combined to determine an unknown variable?
Yes!
PV/T = PV/T
How do you determine the partial pressure of a gas within a mixture?
Pa = XaPtotal
How can you determine the velocity of a gas?
Urms = Sqroot(3RT/M)
Smaller gases have faster velocities!
What are the units of the gas constant R?
L*atm/mol*K
How do you convert molar mass and molar volume to density?
molar mass g/mol
--------------------
molar volume mol/L
What is the ideal gas law equation and what types of gas conditions can it be used for?
PV=nRT
Used to describe gases at normal pressures (1 atm) and normal temperatures (273.15 K).
Also known as STP! Usually 5% deviation is acceptable for use.
DAILY DOUBLE
If an unknown amount of a gas was collected over water at a certain temperature and a certain atmospheric pressure, how do you determine the partial pressure of the unknown amount of collected gas?
Ptotal = Pgas - Pwater
Subtract Pwater from Ptotal!
How does mass affect the rate of effusion?
Rate = 1/sqroot(M)
Larger mass = slower effusion.