CHEMISTRY
April 17th, 2012
Brainteaser FRIDAY 4/20/12
Tell me how your are going to explain what
happened in your experiment and WHY it
happened to the rest of the class today
during your presentations.
Please give me the title of your experiment
too.
Brainteaser MONDAY 4/23/12
According to the KMT, what happens to
pressure when you:
increase the temperature?
Increase volume?
Increase the amount of gas molecules?
Decrease volume?
Objectives
 Pressure and Volume: Boyle’s Law
Understand the law that relates the pressure and volume of
a gas
To do calculations involving this law
 Volume and Temperature: Charles’ Law
To learn about absolute zero.
To learn about the law relating the volume and temperature
of a sample of gas at constant temperature
To do calculations involving this law.
 The Combined Gas Law
 The Ideal Gas Law
To understand the ideal gas law and use it in calculations.
Boyle’s Law: Pressure and Volume
Boyle’s law states that the pressure and
volume of a gas at constant temperature
are inversely proportional.
Inverse relationship
As pressure increases, volume decreases
As pressure decreases, volume increases
This is Boyle’s Law
PV = k
Boyle’s Law
 We can use Boyle’s Law to compare:
Volume, at two pressures
Pressure, at two volumes
 In mathematical terms, this law is expressed
as follows:
Temperature and mass (# of particles)
are constant
Boyle’s Law: Pressure and Volume
A sample of compressed methane has a
volume of 648 mL at a pressure of 503 kPa.
To what pressure would the methane have
to be compressed in order to have a volume
of 216 mL?
Charles’ Law: Temperature & Volume
Charles’s Law states that, for a given
amount of gas at constant pressure, the
volume is directly proportional to the
temperature (in kelvins).
Direct Relationship
 Temperature increases, volume increases
 Temperature decreases, volume decreases
This is Charles’ Law
 V=k
T
Charles’ Law:
At -273 deg C or (O K), the volume of gas
extrapolates to zero.
This temperature is called the absolute zero.
Absolute zero is the lowest possible
theoretical temperature.
Theoretically, at absolute zero, the kinetic
energy of particles is zero, so all motion of gas
particles at that point ceases.
Charles’ Law: Temperature and Volume
We can use Charles’ Law to compare:
Temperature, at two volumes
Volume, at two temperatures
In mathematical terms, this law is expressed
as follows:
Pressure and mass (# of particles) must be
constant
Charles’ Law
A weather balloon contains 5.30 kL of
helium gas when the temperature is 12°C.
At what temperature will the balloon’s
volume have increased to 6.00 kL?
Brainteaser WED/THURS 25-26
A gas at 330 K occupies a volume of 0.250
L. What volume will be occupied if the
temperature drops to 273 K?
Combined Gas Law:
Temperature, Volume, and Pressure
 Boyle’s Law and Charles’ Law can be combined
to look at all 3 variables.
 This is the Combined Gas Law:
 Temperature must be in Kelvin (K)
 K = C + 273
 Use the combined gas law when pressure,
volume or temperature are changing.
Combined Gas Law
A sample of nitrogen monoxide has a
volume of 72.6 mL at a temperature of
16°C and a pressure of 104.1 kPa.
What volume will the sample occupy
at 24°C and 99.3 kPa?