1. Launch: 2/22
 Grab your binder and immediately take a seat!
 Place launch paper and yesterday’s practice questions
on your desk.
 Friday’s Exit Slip Data:
93%!
 Today’s Objectives: I can apply the combined gas law to
relations between temperature, pressure, and volume.

2. Launch: 2/22
 Grab your binder and immediately take a seat!
 Place launch paper and yesterday’s practice questions
on your desk.
 Friday’s Exit Slip Data:
88%
 Today’s Objectives: I can apply the combined gas law to
relations between temperature, pressure, and volume.

3. Launch: 2/22
 Grab your binder and immediately take a seat!
 Place launch paper and yesterday’s practice questions
on your desk.
 Friday’s Exit Slip Data:
97%!
 Today’s Objectives: I can apply the combined gas law to
relations between temperature, pressure, and volume.

4. Launch: 2/22
 Grab your binder and immediately take a seat!
 Place launch paper and yesterday’s practice questions
on your desk.
 Friday’s Exit Slip Data:
95%!
 Today’s Objectives: I can apply the combined gas law to
relations between temperature, pressure, and volume.

5. Launch 2/12
1. Turn to your partner and ask them:
1. What was the most interesting thing that you did
over break?

6. Launch 2/10
2. Using your notes, which pairs of variables
(P V, & T) are directly related?
,

7. Launch 2/10
3. Using your notes, write down the three
equations that we learned that show
relationships between P V, &T.
,

8. Announcements
 Welcome back!
 Exam on Thursday!
 One day of new material
 Two days of review – Jeopardy?
 This week we need to be efficient
 Follow our 7 class rules
 Learn it now! – ask questions
 Class points start over today!

9. February Calendar
Quiz!
Today Exam!

10. Opening
 Today’s Objectives: I can apply the combined gas
law to relations between temperature, pressure,
and volume.
 Standard – CH.4.c
 Today’s Questions: What is the combined gas law?
Simulation!

11. What is the combined
gas law?
Mr. Heffner
2/22/10

12. Review: What are P T, and V?
,
 Temperature (T) measures…
 movement in units of K & °C
 Pressure (P) measures…
 collisions in units of atm & mmHg
 Volume (V) measures…
 space in units of L & mL

13. Review: How are P V, and T related?
,
P&T V&T P&V
T= P T= V V= P
 directly related  directly related  indirectly related
P1 P2 V1 V2
= T = T P1× V1=P2× V2
T1 2 T1 2
d = division Gas Laws

14. What is the combined gas law?
 The combined gas law is…
P1× V1 P2× V2
=
T1 T2

15. How are P & T related?
 There is a 3 step process for solving gas equations:
P1 × V1 P2 × V2
1. Write down =
T1 T2
2. Circle the given units and the letters that go with them
Cross out the letter that is “fixed”, “constant”, or “same”
3. Re-write the equation, plug-in, and solve!

16. Example #1
At constant volume, a gas at 100K and 1 atm is heated to
300K. What is the new gas pressure?
 Step 1: Write down the combined gas law
P1× V1 P2× V2
=
T1 T2

17. Example #1
At constant volume, a gas at 100K and 1 atm is heated to
300K. What is the new gas pressure?
 Step 2: Circle the given units and letters that belong to them.
Cross out the letter that is “fixed”, “constant”, or “same”.
P1× V1 P2× V2
=
T1 T2

18. Example #1
At constant volume, a gas at 100K and 1 atm is heated to
300K. What is the new gas pressure?
 Step 3: Re-write the equation, plug-in, and solve!.
cross-
P1
1atm P2 multiply
= T
✕ 300K
T1
100K 2
(P2)(100K) = (1 atm)(300K)
100K 100K
P2 = 3 atm

19. Example #2
The temperature of a gas is 50°C in a container with a fixed
pressure. If the initial volume of the gas is 200mL, what
would the volume be if the sample was cooled to 25°C?
 Step 1: Write down the combined gas law
P1× V1 P2× V2
=
T1 T2

20. Example #2
The temperature of a gas is 50°C in a container with a fixed
pressure. If the initial volume of the gas is 200mL, what
would the volume be if the sample was cooled to 25°C?
 Step 2: Circle the given units and letters that belong to them.
Cross out the letter that is “fixed”, “constant”, or “same”.
P1× V1 P2× V2
=
T1 T2

21. Example #2
The temperature of a gas is 50°C in a container with a fixed
pressure. If the initial volume of the gas is 200mL, what
would the volume be if the sample was cooled to 25°C?
 Step 3: Re-write the equation, plug-in, and solve!
V1
200mL V2 cross-
multiply
= T
✕ 25°C
T1
50°C 2
(V2)(50°C) =(200mL)(25°C)
50°C 50°C
V2 = 100 mL

22. Example #3
The volume of 200L of Cl2 gas at 200mmHg is decreased to
100L. What is the new gas pressure?
 Step 1: Write down the combined gas law
P1× V1 P2× V2
=
T1 T2

23. Whiteboards
 Work in pairs
 Trade-off marker every question
 You have 60 seconds to calculate the answer
 Follow the steps!
1. Write down the equation
2. Circle and cross out
3. Plug-in and solve!
 Don’t forget units!
 Lift board only when prompted

24. At constant temperature, a
sample of CO2 gas occupies
a volume of 10L at 5 atm.
What will the volume of the
gas be if the pressure is
increased to 2 atm?

25. The volume of Ne gas is
25L at 50K at a fixed
pressure. If the volume is
increased to 100L, what
would the new temperature
be?

26. The pressure of He gas is
100mmHg at 80K. If the
temperature is reduced to
60K, what would the new
pressure be?

27. A sample of CO2 gas
occupies a volume of 1L at
200mmHg. What will the
volume of the gas be if the
pressure is decreased to
100mmHg under constant
temperature?

28. Practice Questions
 Practice question worksheet

29. Closing
 Today’s Objectives: I can apply the combined gas
law to relations between temperature, pressure,
and volume.
 Standard – CH.4.c
 Today’s Questions: What is the combined gas law?
Simulation!

30. Exit Slip
1. Which of the following is the combined gas
law?
a.
V2 V1 c.
T1× V1 T2× V2
= T =
T1 2 P1 P2
b. d.
P1× V1 P2× V2
P1× V1 = P2× V2 =
T1 T2

31. Exit Slip
2. Which of the following is a correct
statement?
a. mL is a unit of pressure
b. mL is a unit of volume, K is a unit of temperature,
and mmHg is a unit of pressure
c. mmHg is a unit of volume, K is a unit of
temperature, and L is a unit of pressure
d. K and L are both units of temperature

32. Exit Slip
3. Choose the right equation.
At a constant temperature, a sample of CO2
gas occupies a volume of 20mL at 2 atm.
What will the volume of the gas be if the
pressure is increased to 20 atm?
a.
P1 P2 c.
= V T1× V1 = T2× V2
V1 2
b. d.
V1 V2
P1× V1 = P2× V2 = T
T1 2

33. Exit Slip
4. The volume of 400mL of Ne gas at
100mmHg is decreased to 200mL at
constant temperature. What is the new gas
pressure?
a. .5 mmHg
b. 200 mmHg
c. 200 mL
d. 2000 mmHg

34. Exit Slip
5. How are P & T related?
a. They are indirectly related.
b. An decrease in temperature increases pressure.
c. They change in the opposite direction
d. They are directly related

35. Homework
 Finish practice questions