Catalyst

1. How is pressure created?2. Give 3 units that pressure is measured with3. 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. What is absolute zero?2. It is 5 K outside. What is the temperature in oC?3. It is 20 oC, what is the temperature in Kelvin?4. What does Boyle’s Law state?5. If I increase the volume will pressure increase or decrease?6. 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 TimeClosing Time• Homework 5.2 – Boyle’s Law Practice