Learning Goals: Behavior of Gases
1. I can use the kinetic molecular theory of gases to describe the properties of gases. (11.1)
A. A gas consists of small particles moving randomly at high velocities.
B. The attractive forces between gas molecules are very small.
C. The actual volume occupied by gas molecules is very small compared to the total
volume that the gas occupies.
D. Gas particles are in constant motion, moving rapidly in straight paths.
E. The average kinetic energy of gas molecules is proportional to the Kelvin
temperature.
2. I can explain the molecular nature of properties that affect gas behavior. (11.1)
A. pressure
B. temperature
C. volume
D. number of particles
3. I can understand that the effects of changing the volume, pressure, temperature, or
amount of particles in a gas sample.
A. I can use the pressure-volume relationship of Boyle’s Law to determine the new
pressure or volume of a certain amount of gas if temperature is held constant. (11.3)
B. I can use the temperature-volume relationship of Charles’s Law to determine the
new temperature or volume of a certain amount of gas if pressure is held constant. (11.4)
C. I can use the pressure-temperature relationship of Gay-Lussac’s Law to determine
the new pressure or temperature of a certain amount of gas if volume is held constant.
(11.5)
D. I can use the combined gas law to find the new pressure, volume, or temperature
of a gas when changes in two of these properties are given. (11.6)
E. I can use Avogadro’s law to describe the relationship between the amount of a gas
and its volume, and use this relationship in calculations. (11.7)
i. I can use Avogadro’s law and molar volume to predict volumes of gases
using stoichiometry in chemical equations. (11.7)
4. I can use the ideal gas law to solve for P, V, T, or n or a gas when given three of the four
values.
5. I can determine the mass or volume of a gas that reacts or forms in a chemical reaction
using molar volume and Avogadro’s law in stoichiometry. (11.7, 11.9)
6. I can use partial pressures of Dalton’s law to calculate the total pressure of a mixture of
gases. (11.10)
Vocabulary
Gas
Vapor Pressure
Kinetic Molecular Theory of Gases
Atmospheric Pressure
STP
Partial Pressure
Achievement Scale
Goal
I can use the kinetic
molecular theory of
gases to describe the
properties of gases.
C Level
I can list the five
points of the
kinetic molecular
theory of gases.
B Level
I can explain the
reasoning behind
the five points in the
kinetic molecular
theory of gases.
I can understand
that the effects of
changing the volume,
pressure,
temperature, or
amount of particles
in a gas sample.
Given a change of
one of the factors
that affect gas
behavior (amount,
temperature,
volume, and
pressure), I can
qualitatively
predict the effect
on another factor if
all other variables
are held constant.
I can determine the
mass or volume of a
gas that reacts or
forms in a chemical
reaction using molar
volume and
Avogadro’s law in
stoichiometry.
Given a quantity in
moles of reactant
or product and a
balanced chemical
equation, I can use
the mole ratio and
molar volume to
calculate the
volume of gaseous
reactants or
products in the
reaction.
Given a change of
one of the factors
that affect gas
behavior (amount,
temperature,
volume, and
pressure), I can
quantitatively use
the gas laws to
calculate the effect
on another factor
and explain why
that effect occurs.
Given the mass of a
reactant or product
and a balanced
chemical equation, I
can use molar mass,
mole ratio, and
molar volume or the
ideal gas law to
calculate the volume
of gaseous reactants
or products in the
reaction.
A Level
I can explain the
reasoning behind the
kinetic molecular
theory of gases and
the reasons why these
assumptions cannot
be made for all of the
states of matter.
Given a change of
multiple factors that
affect gas behavior
(amount,
temperature, volume,
and pressure), I can
quantitatively use the
combined gas law or
the ideal gas law to
calculate the effect on
another factor explain
why that effect occurs.
Given the mass or
gaseous volume of a
reactant or product in
an unbalanced
chemical equation, I
can use molar mass,
mole ratio, and molar
volume or the ideal
gas law to calculate
the gaseous volume of
a reactant or product
in the reaction in an
unbalanced chemical
equation.
Sample Questions
C Level
1) List the five points of the kinetic molecular theory of gases.
2) If the amount of moles of a gas is held constant with a fixed volume, predict the
effect on the pressure of the gas if the temperature was doubled.
3) Given the following balanced chemical equation, N2(g) + O2(g) → 2NO(g), if 2 moles
of nitrogen are reacted with an excess of oxygen, how many liters of NO can be
produced at STP?
B Level
4) Use the kinetic molecular theory of gases to explain why the volume of an inflated
basketball is much greater than the actual volume of all of the air molecules
themselves.
5) If the amount of moles of a gas are held constant with a fixed volume, what is the
new pressure of the gas if initially, the gas is at STP and the temperature is increased
to 30oC. Explain why the pressure increases in this way due to the change in
temperature.
6) Given the following balanced chemical equation, N2(g) + O2(g) → 2NO(g), if 44.8L of
nitrogen are reacted with an excess of oxygen, how many grams of NO can be
produced at STP?
A Level
7) Use the kinetic molecular theory of gases to explain why a bioterrorism attack using
poisonous gas would be potentially much more difficult to control than an attack
using liquid.
8) A 92.0g sample of a liquid is placed in a 25.0L flask. At 140oC the liquid evaporates
completely to give a pressure or 0.900atm. What is the molar mass of the gas?
9) Given the following unbalanced chemical equation, C6H12O6(s) + O2(g) → CO2(g) +
H2O(l), how many liters of CO2 gas can be produced if 30g of C6H12O6 are reacted in
an excess of oxygen at a temperature of 25oC and a pressure of 850mmHg?
Answers:
1) a. Gases are composed of molecules moving randomly at high velocities.
b. Attractive forces in gases are very small.
c. Actual volume of gas molecules is much smaller than the space that the gas
occupies.
d. Gas particles are in constant motion moving rapidly in straight paths.
e. The average kinetic energy of gas particles is proportional to Kelvin temperature.
2) Pressure will also double.
3) 89.2L NO
4) The actual volume of the air molecules in a basketball is very small. However, due to
the fact that the gas molecules are constantly moving at a very high velocity and that
there are large amounts of space in between molecules, the gas exerts a pressure
against the inside of the basketball. This pressure makes it inflate to a volume that
is much greater than the actual volume of the molecules.
5) 1.11 atm or 844mmHg: As the temperature increases, the gas molecules move at a
higher average kinetic energy. These higher speeds cause the gases to collide more
often and thus, exert a higher pressure.
6) 120 g NO
7) Gases would pose a greater bioterrorism threat due to the fact that the gas particles
travel randomly at extremely high speeds due to the kinetic molecular theory of
gases. Through their repeated collisions, the gases spread out in all directions as
they diffuse and are very difficult to both predict and contain. They have very little
attractive forces that keep them together unlike liquids which have stronger
intermolecular forces that keep them attracted to each other. Liquids also move
much more slowly and do not occupy as large of a volume as a similar amount of gas
molecules. For these reasons, it would be easier to contain a contaminated sample
of liquid than a gas.
8) 138.6 g/mol
9) 21.9L O2