Becca Liebendorfer,
Christine Davenport,
Ray Mai, Aliza Edelstein.
C-block
Gas Laws (Chapter 5)
Key TermsPressure (P)- the force exerted per unit of surface area. P= force/area
Barometer- common device used to measure atmospheric pressure
Manometer- device used to measure the pressure of a gas in an experiment
Pascal (Pa)- SI unit of pressure
Standard atmosphere (atm)- another unit of pressure (large)
Millimeter of mercury (mmHg)- common pressure unit based on measurement
with a barometer or manometer
1 torr= 1mmHg= 1/760atm= 101.325/760kPa= 133.322Pa
Ideal gas- exhibits simple linear relationships among volume, pressure
temperature and amount
Boyle’s Law- V [is directly proportional to] 1/P (T and n fixed)
- at constant temperature, the volume occupied by a fixed amount of gas
is inversely proportional to the applied [external] pressure
Charles’s Law- V [is directly proportional to] T (P and n fixed)
- at constant pressure, the volume occupied by a fixed amount of gas is
directly proportional to its absolute temperature
Avogadro’s Law- V [is directly proportional to] n (P and T fixed)
- at fixed temperature and pressure, equal volumes of any ideal gas
contain equal numbers of particles (or moles)
standard temperature and pressure (STP)- 0°C (273.15K) and 1atm (760 torr)
standard molar volume- 22.4141L or 22.4L (to 3SF)
ideal gas law- PV=nRT
universal gas constant (R)- a proportionality constant
 8.314 kPa*L/mol*K= 0.08206 L*atm/mol*K= 62.36mmHg*L/mol*K
partial pressure- portion of the total pressure of the mixture, that is the same
pressure it would exert by itself
Dalton’s Law of partial pressure- in a mixture of unreacting gases, the total
pressure is the sum of the partial pressure of the individual gas
Mole fraction (x)- component in a mixture contributes a fraction of the total
number of moles in the mixture
Kinetic molecular theory- draws conclusions through mathematical derivations
RMS speed- A molecule moving at this speed has the average kinetic energy
Effusion- the process by which a gas escapes from its container through a tiny
hole into an evacuated
Graham’s Law of effusion- the rate of effusion of a gas is inversely proportional
to the square root of its molar mass
Diffusion- the movement of one gas though another
1. What is the density of a gas that is 1.996g with a volume of 1190cm3?
a. .001677g/L
2.
3.
4.
5.
6.
7.
8.
9.
b. 1.677g/L*
c. 596.2L/g
d. .5962L/g
3.200 g of a gas is 5.080 moles. What is its molar mass?
a. 1.588 g/mol
b. 16.26 g/mol
c. .6299g/mol*
d. 5.015x10-24 g/mol
Oxygen gas effuses through a capillary in 2.00 seconds. An unknown gas of the
same volume effuses in 4.00 seconds. What is the molar mass of the unknown
gas?
a. .0156 g/mol*
b. .0313 g/mol
c. 32.00 g/mol
d. 64.00 g/mol
In a closed end manometer, the mercury level was 540.mm higher on the closed
end than on the gas end. What was the gas pressure?
a. 1290 mmHg
b. 210. mmHg
c. 440. mmHg
d. 540. mmHg*
If the Thirsty Bird (think Gay Lussac’s gas law) dips his head in water and cools
down from 50◦C to 30◦C, and the pressure in his belly was originally 1 atm, what
was the pressure after his drink?
a. 1.67 atm
b. .938 atm*
c. 1.07 atm
d. .600 atm
A snake balloon has .00100 moles of air in it and a volume of .100 mL. If I blow
.028 moles of air into it, what is its volume?
a. 2.80 L
b. 28.0 L*
c. .0357 L
d. .3571 L
T1=207K. T2=301K. n1=.400 moles. n2=.275 mol. Which law is this?
a. Unnamed*
b. Boyles’
c. Charles’
d. Graham’s
An He molecule, weighing 4.0 g/mol at 200K has ____times as much K.E. as an
H2 molecule, weighing 2.0 g/mol, at 200K?
a. 1.00 times as much*
b. 2.00 times as much
c. .500 times as much
d. 0. times as much
H2 molecules (2.00 g/mol) at 200.K go ____as fast as He molecules (4.00 g/mol)
at 600.K?
a. .667 times as fast
b. 6.00 times as fast
c. 2.45 times as fast
d. .817 times as fast*
10. Charles’ law: a gas with a volume of 700.mL at 300.K has what volume at 383K?
a. 621 L
b. 789 L
c. .789 L
d. .621 L
Gas Law Questions
In an open end manometer with an atmospheric pressure of 37.8 kPa, the Hg level was
27.3 mm higher on the left. What is the gas pressure?
a. 3.64 kPa
b. 22.3 kPa
c. 34.2 kPa *
d. 35.8 kPa
At 27 degrees Celsius, a gas, was at 321 kPa, at what temperature would it be at 1.00
atm?
a. 710 Kelvin *
b. 435 Kelvin
c. 813 Kelvin
d. 127 Kelvin
7.36 grams of a gas occupies 2.67 liters at 17 degrees Celsius and 115.2 kPa. How many
moles of gas is it?
a. .449 moles
b. .120 moles
c. .372
d. .132 moles*
What is the density of MgO at 731 K in 7.32 psi?
a. .491 g/l
b. .334 g/l*
c. .234 g/l
d. .329g/l
What is the molecular weight of a gas that has a mass of 13.2 grams, a volume of 3.7
liters, at 32 degrees Celsius, and 117 kPa?
a. 68.2 g/mol
b. 77.3 g/mol*
c. 60.8g/mol
d. 79.9 g/mol