The document describes the kinetic molecular theory of gases and gas laws. It states that gases are composed of particles that are in constant, random motion with empty space between them. The kinetic molecular theory explains gas behavior in terms of four variables: number of moles (n), volume (V), temperature (T), and pressure (P). The ideal gas law describes the relationship between these four variables. Boyle's, Charles', and Lussac's laws are specific relationships between some of the gas law variables when others are held constant. Sample problems demonstrate how to use the gas laws to calculate values.

1. Kinetic Molecular Theory of Gases

2. Gas Laws Introduction Video

3.  A gas consists of very small particles
 The distances between gas particles are relatively large
 Gas particles are in constant, random motion
 There is no attractive force between particles of gas
Kinetic Molecular Theory Describes the Behavior
of Gases

4.  Moles (n) – the amount of gas
 Volume (V) – the size of the container that holds the gas in liters (L)
 Temperature (T) – the speed or kinetic energy of the particles in
Kelvin (K)
 Pressure (P) – the outward push of gas particles on their container
in atmospheres (atm) or millimeters of mercury (mm
Hg) or pounds per square inch (psi)
Variables That Effect Gases

5.  The Ideal Gas law attempts to describe the behavior of real gases
under ideal conditions
 Illustrates the relationship between pressure, volume, temperature and
moles
 Formula: PV = nRT
R = the ideal gas constant
Ideal Gas Law

6.  How many moles of hydrogen gas occupy 0.500L at STP?
STEP 1: PV = nRT P = 1.0atm n = ? T = 273K
V = 0.500L R = 0.0821atm•L/mol•K
STEP 2: n = PV
RT
STEP 3: n = (1atm)(0.500L)______
(0.821 atm•L/mol•K)(273K)
STEP 4: n = 0.0223 moles
Ideal Gas Law Practice Problem
At STP:
P = 1.0atm
V = 22.4L
n = 1.0 mole
T = 273K
R = 0.821 atm•L/mol•K

7.  Boyle’s Law = Pressure-Volume Relationship
 The pressure and volume of a sample of gas at constant temperature are
inversely proportional to each other
 As one goes up , the other goes down
 Formula: P1V1 = P2V2
Boyle’s Law

8. A Graph of Boyle’s Law
 Pressure is inversely
proportional to
volume when
temperature is held
constant
 Temperature is held
constant

9.  The gas in a 20.0mL container has a pressure of 2.77atm. When the gas
is transferred to a 34.0mL container at the same temperature, what is the
new pressure of the gas?
STEP 1: P1V1 = P2V2 P1 = 2.77atm V1 = 20.0mL
P2 = ? V2 = 34.0mL
STEP 2: P2 = P1V1
V2
STEP 3: P2 = 20.0mL (2.77atm)
34.0mL
STEP 4: P2 = 1.63atm
Boyle’s Law Practice Problem

10.  According to Boyle’s Law, you can’t fully inflate a balloon
at high altitude other wise what will happen as it rises
through the atmosphere?
Boyle’s Law Question
HINT:

11.  Charles’ Law = Temperature-Volume Relationship
 At constant pressure, the volume of a fixed amount of gas is directly
proportional to its absolute temperature
 Formula: V1 = V2
T1 T2
Charles’ Law

12. A Graph of Charles’ Law
 The volume of a gas is
directly proportional
to temperature
 Pressure is held
constant

13.  What will be the volume of a gas sample at 355K if its volume at 273K is
8.57L?
 STEP 1: V1 = V2 V1 = 8.57L T1 = 273K
T1 T2 V2 = ? T2 = 355K
STEP 2: V2 = V1T2
T1
STEP 3: V2 = 8.57L (355K)
273K
STEP 4: V2 = 11.1L
Charles’ Law Practice Problem

14.  According to Charles’ Law, if you take a balloon filled with
air and lower its temperature, what will happen to the
balloon?
Charles’ Law Question
HINT:

15.  Lussac’s Law = Temperature-Pressure Relationship
 If a volume of a sample of gas remains constant, the temperature of a
fixed amount of gas is directly proportional to its pressure
 Formula: P1 = P2
T1 T2
Lussac’s Law

16. A Graph of Lussac’s Law
 Pressure and
temperature of a gas
are directly related
 Volume is held
constant

17.  The gas left in a used aerosol can is at a pressure of 2.03atm at 25˚C. If
this can is thrown onto a fire, what is the pressure of the gas when its
temperature reaches 928˚C?
 STEP 1: P1 = P2 P1 = 2.03atm T1 = 25˚C
T1 T2 P2 = ? T2 = 928˚C
STEP 2: P2 = P1T2
T1
STEP 3: P2 = 2.03atm (1201K)
298K
STEP 4: P2 = 8.18atm
Lussac’s Law Practice Problem

18.  A gas BBQ grill uses propane gas stored in a rigid tank.
What happens to the pressure of the propane when the
tank if left outside on a very hot summer day?
Lussac’s Law Question