Name: ___________________________________________ Period: _____ Teacher: ______________
Gas Laws (Pre-AP)
Jan. 30
31
Feb. 1-2
3
6
7
8-9
10
13
14
15-16
17
Kinetic Molecular
Theory


Define the kinetic molecular theory
Use the kinetic-molecular theory to explain
the behavior of gases
 Differentiate between effusion and
diffusion.
 Describe how mass affects the rates of
diffusion and effusion.
 Compare the rate of effusion of various
gaseous molecules.
Gas Pressure

*Use Henry’s Law to discuss solubility of
gases as a function of gas pressure*
 Summarize why atmospheric pressure exists
and generalize how it varies with altitude.
 Indicate how gas pressure is measured and
interpret how to convert from kPa to mm to
atm to psi.
 Calculate the partial pressure of a gas
Kinetic Molecular
Theory Khan
Academy
Relationship between
p, v, t
 Categorize or breakdown how changes in
one of these variables affects the others: gas
volume, temp, and pressure.
 Arrange the Combined Gas Law, Boyle’s
law, Charles’s law, Avogadro’s law, and
Gay-Lussac’s law in terms of pressure,
volume, moles, and temperature
Gas Law Problems
 Apply the three gas laws (or the combined
gas law) to problems involving the
pressure, temperature, moles, and volume
of a gas
 Apply the combined gas law to problems
involving the pressure, temperature, and
volume of a gas
 Relate numbers of particles and volumes by
using Avogadro’s principle.
Gas Laws Explained!
Ideal Gas Law
 Relate the amount of gas present to its
pressure, temperature, and volume by using
the ideal gas law.
 *Adapt the ideal gas law and grams of gas
to determine volume or pressure at nonstandard conditions*
 *Adapt the ideal gas law to determine
molar density of a gas at non-standard
conditions*
Ideal Gas Law
Ideal Gas Example
Warm-ups
Monday, Feb. 6
Tuesday, Feb. 7
Wednesday, Feb. 8
Friday, Feb. 10
Monday, Feb. 13
Tuesday, Feb. 14
Notes:
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14.2 The Gas Laws
There are four laws that define the behavior of gases in simple, controlled scenarios.
1. Boyle’s Law for Pressure-Volume Changes- Robert Boyle (1662)-Anglo/Irish chemist
 For a given mass of contained gas at constant temperature, the ___________of the gas
varies inversely with ___________.
P1 V1 = P2 V2
“We Boyle Peas
and Vegetables”
Ex. A gas is collected in a 242 mL container. The pressure of the gas in the container is measured and
determined to be 87.6 kPa. What is the volume of this gas at 101.3 kPa? Assume the temperature is
constant.
2. Charles’ Law for Temperature-Volume Changes-Jacques Charles (1787)- French
physicist/balloonist
 The volume of a fixed mass of gas is ______________proportional to its ___________
temperature if the pressure is kept constant. Temperature must be in Kelvin!!
Ex. A sample of gas at 15oC and 1 atm has a volume of 2.58 L. What volume will this gas
occupy at 38oC and 1 atm?
3. Gay-Lussac’s Law for Temperature-Pressure Changes- Joseph Gay-Lussac(1802)- French
chemist
 The pressure of a gas is _____________ proportional to the ___________ temperature
if the volume is kept constant.
Ex. A 2.00 L flask contains helium gas at a pressure of 685 torr and a temperature of
0oC. What would be the pressure in a flask if the temperature is increased to 150.oC?
4. The Combined Gas Law- combination of the variables from each gas law.
 By canceling out terms remaining constant, we can derive Boyle’s, Charles’, and GayLussac’s laws.
Ex. If a helium-filled balloon has a volume of 3.40 L at 25.0oC and 120.0 kPa, what is its
volume at STP, assuming the number of particles is constant?
*** “n” represents number of moles…the relationship of moles in a sample to volume
(or pressure and temperature by extension) is shown by Avogadro’s Law
“Charlie Brown
Christmas was on
TV”
“Gayle drives a PT
Cruiser.”
Temperature must be
in Kelvin!
𝑃1 𝑉1
𝑛1 𝑇1
=
𝑃2 𝑉2
𝑛2 𝑇2
“Peas and
Vegetables on the
Table”
Combined Gas Laws Practice
Directions: For each of the problems assigned, state the law that applies; then solve the problem showing all of
your work, including units.
1. Correct the volume of 259 cm3 of oxygen gas at 112 kPa to the volume at standard pressure.
2. The temperature of CO2 gas at 99.3 mmHg was measured at 455 K. What will be the new temperature if the
pressure is adjusted to 202.6 mmHg? Assume constant volume.
3. The volume of a gas is observed to change from 62.4 cm3 to 47.3 cm3 as the pressure increases. The original
pressure is 117 kPa. What is the final pressure after the volume change? (Assume constant temperature.)
4. The volume of a sample of carbon monoxide is 354 mL at 3.52 atm. What will the volume be when the pressure
is reduced to 1.85 atm, assuming the temperature is constant?
5. A gas at constant pressure occupies 400.0 mL at 50.0ºC. What volume will it have at 300.0ºC?
6. A cylinder with a movable piston contains .005 mol of helium, He, at room temperature. More helium was
added to the cylinder and the volume was adjusted so that the gas pressure remained the same. How many moles
of helium are now in the cylinder if the volume was changed from 2.00 L to 2.70 L? (The temperature was held
constant.) How many grams is this?
7. A gas occupies 105 mL at 100.0 K. At what Celsius temperature will its volume be 140 mL?
8. A gas at 300K occupies 6.50 L at a pressure of 3.50 atm. What will its pressure be at 250 K if its volume is
reduced to 4.80 L?
9. The volume of NO2 gas at 99.3 kPa was measured at 455 cm3 . What will the volume be if the pressure is
adjusted to 202.6 kPa? The temperature changes from 300 K to standard temperature.
10. 5.00 L of oxygen is known to contain 0.965 mol. If the amount of oxygen is increased to 57.6 grams, what new
volume will result (at an unchanged temperature and pressure)?
Ideal Gases
Gases often are placed in uncontrolled environments where temperature,
pressure and volume are changing. Under those conditions, gases may not
behave as expected.



Ideal gas- follows the _____________ at all conditions of temperature and
pressure. - don’t exist.
Real gases can be _____________ and sometimes solidified; ideal gases
cannot.
Gases behave most ideally at _________ temperature and __________
pressure.
The Ideal Gas Law
 Allows us to include amount of gas (moles) in our calculations.
Ex 1. A 5.0 L flask contains 0.60 g O2 at a temperature of 22oC. What is
the pressure (in atm) inside the flask?
PV = nRT
“Piv Nert”
P = pressure in atm
V = volume in L
n = # of moles
R = ideal gas constant = 0.0821
T = temperature in Kelvin
Pressure Conversions – Need to
Memorize!!!





1 atm
760 mmHg
760 torr
101.325 kPa
14.7 psi
Ex 2. How many grams of krypton are present in a 600. mL container at 1010oC in which the pressure of
krypton is 10.0 atm? How many atoms is this?
Ex 3. If I have an unknown quantity of gas at a pressure of 121.6 kPa, a volume of 31 liters, and a
temperature of 87 o C, how many moles of gas do I have?
Ex 4. What volume will 20.0g of Argon occupy at STP?
We can use PV = nRT to solve almost any gas problem. If P & V change while n & R & T remain constant,
then P1V1 = nRT & P2V2 = nRT so P1V1 = P2V2.
Gases: Mixtures and Movements
Dalton’s Law of Partial Pressure
 At constant volume and temperature, the total pressure exerted by a mixture of
gases is equal to the _______ of the partial pressures.
Ptotal = P1 + P2 + P 3
Example: Determine the total pressure of a gas mixture that contains nitrogen and oxygen if the partial
pressure of the nitrogen is 725 mm Hg and the partial pressure of the oxygen is 426 mm Hg.

Gases are often collected by water displacement. The total of the ________ pressure plus the
_______________ pressure is equal to the atmospheric pressure. When we work a problem like this we
must always look up and subtract the water vapor pressure to get the gas pressure.
Example: A sample of N2 gas is collected by the downward displacement of water from an inverted bottle.
What is the partial pressure of the N2 gas at 20.0oC, if the atmospheric pressure is 752 mm Hg? The water
vapor pressure is 17.5 mm Hg at 20.0oC.
Solving for the molecular weight (molar mass) of an unknown gas

Gas pressure, temperature, mass, and volume can be used to calculate the
molecular weight of an unknown gas. This can help identify the gas. A
modification of the ideal gas law can be used for this. We call this the
"molecular weight kitty cat"
MW= molecular weight
d=density in g/L
Ex. At 22.0oC and a pressure of 755 torr, a gas was found to have a density of 1.14 g/L. What was its gfm?
Ex. What density does oxygen gas have at 25.0oC and 745 torr?
Ex. Uranium hexafluoride is a solid at room temperature, but it boils at 56oC. Determine the density of
uranium hexafluoride at 60.oC and 745 torr.
At STP, the density or MW of a gas can be determined by density x 22.4L = MW or MW/22.4L = density in g/L
Gas Stoichiometry Problems
1) What volume of oxygen (in L) at STP would be produced by the decomposition of 0.600 moles of
potassium chlorate?
____KClO3  ____KCl + ______O2
2) What volume of chlorine gas is needed to completely react with 54.0 g potassium iodide at a temperature of
37 oC and 110.4 kPa?
____KI + ____Cl2  ____KCl + ____I2
3) How many liters of oxygen will be required at a temperature of 305 K and 3.00 atm of pressure to consume
25.0 grams of methane gas (CH4) in a combustion reaction?
Equation: ____________________________________________________
4) Hydrazine reacts with oxygen: N2H4(g) + O2(g)  N2(g) + 2H2O(g)
a. If a solution contains 180. g of hydrazine, what is the maximum volume of oxygen gas that will react
with the hydrazine if the O2 is at a pressure of 750. mmHg and 21.0°C?
b. Assume the oxygen to burn the hydrazine is in a 450. L tank at 26°C. If you want to completely burn a
10.0 kg sample of hydrazine, to what pressure should you fill the oxygen tank in order to have sufficient
oxygen?
5) If an unknown mass of nitroglycerine, C3H5N3O9, explodes and releases gases with a temperature of
1985°C and a volume of 4.50 L. If the pressure of H2O is 4104mmHg, what was the mass of nitroglycerine
that reacted?
4 C3H5N3O9(s)  12 CO2(g) + 10 H2O(g) + 6 N2(g) + O2(g)
6) What volume of oxygen gas at 40oC and a pressure of 403.8kPa, will be needed to react completely with
2.94 moles of NH3 gas?
4NH3(g) + 7O2(g)  4NO2(g) + 6H2O(l)
Chapter 13 and 14 Practice Test
Multiple Choice
1.
A breathing mixture used by deep-sea divers contains helium, oxygen, and carbon dioxide. What is the partial
pressure of oxygen at a total pressure of 1 atm if P He=609.5 mmHg and PCO2 = 0.5 mmHg?
a. 760 mmHg
c. 150 mmHg
b. 500 mmHg
d. 100 mmHg
2.
What is the SI unit of pressure?
a. Candela
b. Mole
c.
d.
Pascal
Newton
e.
Joule
3.
Equal volumes of nitrogen and oxygen, at the same temperature and pressure, would:
a. have the same mass
c. contain different numbers of particles
b. contain the same number of particles
d. have different kinetic energies
4.
What happens to the temperature of a gas when it is compressed?
a. The temperature increases.
b. The temperature does not change.
c.
The temperature decreases.
5.
Real gases behave most like ideal gases under which set of experimental conditions?
a. low temperature, high pressure
c. low temperature, low pressure
b. high temperature, low pressure
d. high temperature, high pressure
e. net
f. crystal system
6.
The total pressure of a mixture of gases is
a. obtained by multiplying the individual pressures by the number of moles and averaging.
b. the sum of the partial pressures of the components.
c. dependent only upon the pressure of the gas which is present to the greatest extent.
d. the product of the individual pressures.
7.
Under similar conditions, which gas diffuses most rapidly through a small opening?
a. CH4
c. SO2
b. CO2
d. O2
8.
9.
What instrument is normally used to measure atmospheric pressure?
a. Thermometer
b. Barometer
Air, being about 16 times as dense as hydrogen, diffuses
a. sixteen times as fast
b. four times as fast
c. 1/16 as fast
c.
d.
Hydrometer
Spectrometer
d.
e.
1/4 as fast
1/2 as fast
10. Which is the highest pressure?
a. 1.2 atm
b. 101 Pa
c. 101 kPa
d. 748 torr
11. Boyle's law states that:
a. the volume of a gas varies inversely with pressure
b. The volume of a gas varies directly with pressure
c. the temperature of a gas varies inversely with pressure
d. The temperature of a gas varies directly with pressure
12. Charles' Law states that:
a. the pressure of a gas is inversely proportional to its Kelvin temperature
b. the volume of a gas is directly proportional to its Kelvin temperature
c. the pressure of a gas is directly proportional to its Kelvin temperature
d. the volume of a gas is inversely proportional to its Kelvin temperature..
e.
Cl2
Work Out Problems
1.
A gas bubble has a volume of 0.850 mL at the bottom of a lake, where the pressure is 3.46 atm. What is the volume
of the bubble at the surface of the lake, where the pressure is 1.00 atm? Assume that the temperature is constant.
2.
A balloon filled with air has a volume of 4.25 L at 30°C and is placed in a freezer at -10°C. What is the volume of the
balloon at -10°C?
3.
Calculate the volume that 21.0 mol of ammonia gas occupies at 37°C and 600 torr.
4.
1.00 g of a gaseous compound of boron and hydrogen occupies 0.820 L at 1.00 atm and 3°C. What is the molecular
weight of the compound?
5.
A sample of gas is in a 50.0 mL container at a pressure of 645 torr and a temperature of 25°C. The entire sample is
heated to a temperature of 35°C and transferred to a new container whose volume is 65.0 mL. Determine the pressure
of the gas in the second container.
6.
Calculate the volume of 3.00 g of helium at 27°C and 1.00 atm pressure.
7.
Calculate the molecular weight of a gas if 6.00 g occupies 4.06 L at 1.05 atm and 22°C.
8.
A sample of a gas occupies a volume of 14.0 L at 27°C and 2.00 atm pressure. What is the volume of this sample at
STP?
9.
What mass of Mg will react with HCl to produce 5.00 x 102 mL of hydrogen gas at 25°C and 0.986 atm pressure?