Catalyst
1. How is pressure created?
2. Give 3 units that pressure is measured with
3. How does the motion of gas molecules
explain diffusion?
End
JUST HOW COLD CAN IT GET?
Justify – TPS
• What is the coldest possible temperature?
LECTURE 5.2 – TEMPERATURE
SCALES AND BOYLE’S LAW
Today’s Learning Targets
• LT 5.3 – I can define what STP is on an exit ticket
• LT 5.4 – I can discuss how the kinetic energy of a gas molecules is related
to the temperature of the gas mixture on an exit ticket
• LT 5.5 – I can define what absolute zero and relate it to the Kelvin
temperature scale on an exit ticket
• LT 5.6 – I can convert between the Kelvin and Celsius temperature scales
on an exit ticket
• LT 5.7 – I can explain Boyle’s Law, how it relates pressure and volume,
and I can calculate pressure and volume values for a given problem on
an exit ticket
What are the temperature scales?
I. Temperature
• The temperature that we
feel is created by the
movement of atoms.
• The movement of gas
molecules in the air creates
our observable temperature
• The temperature is a
measurement of the average
energy of a sample
II. Temperature Scales
• The 2 main
temperature scales in
chemistry are the
Celsius and Kelvin
scales
• The Celsius scale sets
the freezing point of
water at 0 oC and the
boiling point of water
at 100 oC
What is STP?
I. STP
• When working with gases,
reactions are normally
carried out under standard
temperature and pressure
or STP
• STP is defined as 273 K and 1
atm
What is absolute zero?
I. Kelvin Scale
• The other unit of
temperature used in
chemistry is the Kelvin
scale.
• The Kelvin scale sets 0 K
as being absolute zero.
II. Absolute Zero
• Absolute zero is the
temperature at which all
molecular motion stops.
• Coldest possible
temperature
• It is impossible to go
below absolute zero (0 K)
because molecular
motion has stopped at
this point.
How do we convert between Celsius and Kelvin
I. Converting Between Kelvin and Celsius
• To convert from Celsius to Kelvin:
Kelvin = Co + 273
• To convert from Kelvin to Celsius:
Celsius = Kelvin – 273
Class Example
• It is 33 oC outside, what is this temperature in
Kelvin?
Table Talk
• If I have something at 298 K, what
temperature is it in Celsius?
Stop and Jot
• You measure a reaction at 1250 oC, what is the
temperature in Kelvin?
SUMMARIZE
Gas Phase/Absolute Zero Game
• A fun take on red light,
green light.
• You are a molecule
• When the person who is
the caller says gas phase
you move
• When the person who is
the caller says absolute
zero you stop
• Why do molecules stop at
absolute zero?
How Are Pressure and Volume Related?
• Play with the syringe at your table
• With your table, hypothesize about how
pressure and volume are related.
• Does pressure increase or decrease as volume
is decreased?
Justify – TPS
• Why does it get harder to push down on the
syringe the more you push down? How does
pressure change?
What is Boyle’s Law?
I. Boyle’s Law
• If we keep temperature constant,
then volume and pressure are
inversely related. As one goes up
the other goes down
• If the container gets larger the gas
molecules are hitting the walls at
a less frequent rate.
• Therefore, by decreasing the
volume of a container, we are
increasing the pressure.
Boyle’s Law
Graph of Boyle’s Law
This is an inverse
relationship! As one
goes up the other goes
down!
How do we calculate pressure and volume?
How do we calculate pressure and volume?
I. Boyle’s Law Equation
• Boyle’s Law states that pressure and volume
are described by the equation:
PiVi=PfVf
Class Example
• A given sample of gas occupies 523 mL at 1
atm. The pressure is increased to 2 atm, while
the temperature remains the same. What is
the new volume of the gas?
Table Talk
• A sample of oxygen has a volume of 500 mL at
a pressure of 2 atm. What will the volume be
if the pressure is increased to 5 atm?
Stop and Jot
• A sample of as in a syringe has a volume of 10
mL and a pressure of 6 atm. What is the new
volume if the pressure is decreased to 3 atm?
SUMMARIZE
Relay Races
Relay Race Questions
1.
2.
3.
4.
5.
6.
What is absolute zero?
It is 5 K outside. What is the temperature in oC?
It is 20 oC, what is the temperature in Kelvin?
What does Boyle’s Law state?
If I increase the volume will pressure increase or decrease?
I start with a gas that is 5 atm and a volume of 500 mL. If the final
volume is 1500 mL, then what is the final pressure?
Exit Ticket
1. What is the coldest possible temperature?
What happens at this point?
2. What are the temperature and pressure for
STP?
3. What does Boyle’s Law say about the
relationship between pressure and volume?
4. A sample of as in a syringe has a volume of
10 L and a pressure of 3 atm. What is the
new volume if the pressure is decreased to
1.5 atm?
Rate Yourself
• Rate yourself 1 – 4 on LT 5.3 to 5.7
Happy Thanksgiving!
Closing Time
• Homework 5.2 – Boyle’s Law Practice