I prepared and used this handout during my practice teaching. :) ;)

1. Gas Laws
Gas Laws- deal with how gases behave with respect to pressure, volume, temperature and
amount. It is a simple mathematical relationship between the pressure, temperature, volume and
amount/mole.
 Pressure, volume, temperature are the four fundamental measurable properties of gas.
Wherein pressure (P), is the force (F) that acts on a given area (A). The SI unit for
pressure is Pascal (Pa). Standard atmosphere (atm) and torr or mm Hg (millimeters of
mercury) are also used as units for pressure.
 Volume (V) is the unit for three dimensional measure of space that comprises a length, a
width and a height. The SI unit is liters.
 Temperature (T) is a measure of heat and cold often measurable with thermometer. The
temperature of a gas is generally express in Fahrenheit (˚F), Centigrade or Celsius (˚C) and
Kelvin (K).
 Amount or Number of Moles is another measurable property of gas that determines its
mass.
I. Boyle’s Law (The Pressure-Volume Relationship)
- Proponent chemist: Robert Boyle
- It states that the volume of a given mass of a gas held at a constant temperature is
inversely proportional to its pressure.
a. As the volume increases the pressure decreases.
b. As the volume decreases, the pressure increases.
- When two measurements are inversely proportional, one gets smaller as the other gets
bigger.
- To compute for Boyle’s Law use this formula: P1V1 = P2V2
- Pressure SI unit is PASCAL. Volume SI unit is LITER.
Sample Problem:
If a gas at 25.0 °C occupies 3.60 liters at a pressure of 1.00 atm, what will be its volume at a
pressure of 2.50 atm?
P1= 1.00 atm V1= 3.6 L P2= 2.5 atm V2= X
P1V1 = P2V2
(3.6 L) (1.00 atm) = X (2.5 atm)
3.6 = X (2.5 atm) * Divide 3.6 by 2.5 to find the value of X.
X = 3.6/2.5
X = 1.44 L

2. Practice Problems
1. A science class puts a balloon
containing 1.25 L of air at 101 kPa into
a bell jar. Using an air pump, the class
removes some of the air in the jar,
causing the balloon to expand to a
volume of 2.25 L. Assuming a constant
temperature, what is the new pressure
inside the jar?
2. A small balloon is inflated with helium
at 102 kPa to a volume of 2.12 L.
According to the balloon’s manu-
facturer, if the balloon is stretched to a
volume of 4.25 L, the balloon will pop.
If the balloon were released, at what
pressure would the balloon pop?
Assume constant temperature through-
out.
Activity:
Compute for the following. Show
your computations and write your answers
on a one whole sheet of paper.
1. A gas occupies 1.56 L at 1.00 atm. What
will be the volume of this gas if the
pressure becomes 3.00 atm?
2. A gas occupies 11.2 liters at 0.860 atm.
What is the pressure if the volume
becomes 15.0 L?
3. A gas occupies 4.31 liters at a pressure of
0.755 atm. Determine the volume if the
pressure is increased to 1.25 atm.
4. .At a sewage treatment plant, methane is
gathered for energy use. If 75 L of
methane is produced at 94 kPa, how
many liters would be produced at 100
kPa? Assume temperature remains
constant throughout.
5. A sample of carbon dioxide occupies a
volume of 3.50 liters at 125 kPa pressure.
What pressure would the gas exert if the
volume was decreased to 2.00 liters?
6. Helium occupies a volume of 15.0 liters at
432 Pa pressure. What would be the new
volume if the final pressure is 400 Pa?

3. II. Charles’ Law
- The Temperature-Volume Relationship.
- Proponent: Jacques Charles
- Charles' Law states: the volume of a fixed amount of gas maintained at constant
pressure is directly proportional to its absolute temperature.
a. As the temperature increases, the volume also increases.
b. As the temperature decreases, the volume also decreases.
- When two measurements are directly proportional, as one changes in size the other
undergoes the same size change.
- Charles' Law is expressed by the equation:
- Temperatures used in all Gas Law calculations must be in Kelvin (K) units.
Conversion: K = o
C + 273
-
Sample Problem:
A fixed quantity of gas at 23 o
C exhibits a pressure of 735 torr and occupies a volume of
5.22 liters. What volume will the gas occupy if the temperature is increased to 165 o
C while the
pressure is held constant?
Practice Problems
1. What is the volume of the air in a balloon that occupies 0.620 L at 25C if the temperature is
lowered to 0.00C?
2. The Celsius temperature of a 3.00-L sample of gas is lowered from 80.0C to 30.0C. What
will be the resulting volume of this gas?
7.72 L

4. Activity
Compute for the following items. Show your computations in the space provided.
1. A gas occupies 1.00 L at standard temperature. What is the volume at 333.0 °C?
2. The temperature of a 4.00 L sample of gas is changed from 10.0 °C to 20.0 °C. What will the
volume of this gas be at the new temperature if the pressure is held constant?
3. When 50.0 liters of oxygen at 20.0 °C is compressed to 5.00 liters, what must the new
temperature be to maintain constant pressure?
4. A gas syringe contains 56.05 liters of a gas at 315.1 K. Determine the volume that the gas will
occupy if the temperature is increased to 380.5 K.
5. If pressure is known to be constant, what was the original volume of a sample of gas that was
collected at 90 o
C when its volume is 200 liters at 15 o
C?