1. Great Huskies in Science!
Catalyst:
The volume of 400 mL of Cl gas at 400 mm Hg is decreased to 200 mL at constant temperature. What is the new gas pressure?
Under which of the following circumstances might a gas decrease in volume
a. The gas is held at constant pressure
b. The gas remains under uniform temp.
c. The gas is placed under increasing pressure
d. The gas undergoes a decrease in pressure

2. Labs Next Week
You must qualify this week to be able to participate in the lab next week.
I need to feel confident that you can use the supplies safely and correctly.

3. Today’s Objectives SWBAT explain what STP is and why chemists use it.
SWBAT calculate using the Ideal Gas Law

4. Combines Boyle’s, Gay-Lussac’s, and Charles Law
Combined Gas Laws
We can combine Boyle’s Law, Charles Law, and Gay-Lussac’s Law into one equation.
The combined Gas Law equation is:
Combines Boyle’s, Gay-Lussac’s, and Charles Law

5. STP
Scientists use the idea of standard temperature and pressure (STP) to describe gases.
Scientists have designated STP as being 1 atm and 0 oC or 273 K.
Many gas law problems use STP
Note – At STP 1 mole of any gas occupies a volume of 22.4 L. This is regardless of the identity of the gas.

6. Quick Write
What are the equations for Charles Law, Boyle’s Law, and Gay-Lussac’s Law?
What do they say about temperature, pressure, and volume?

7. Gas Law Recap
Boyle’s Law tells us pressure and volume are inversely related so:
PiVi=PfVf
Gay-Lussac’s Law tells us that pressure and temperature are directly related so:
Charles Law tells us that volume and pressure are directly related so:

8. Ideal Gas Law
Combines Boyle’s, Charles , and Gay-Lussac’s Law into one single equation.
An ideal gas is an imaginary gas whose particles are infinitely small and do not interact with each other.
The law works best at room temperature and atmospheric pressure

9. PV=nRT The Ideal Gas Law The Ideal Gas Law is: P=pressure
V=volume in L
n=moles
R=Gas constant
T=temperature in Kelvin.

10. Steps to Solve Ideal Gas Law Problems
Read and annotate the problem
Identify all variables that are given in the problem. Identify what is not given in the problem.
Convert all temperatures to Kelvin and all volumes to liters.
Plug in givens to Ideal Gas Law and solve for unknowns.
Check that you did this correctly by canceling out the units.

11. Class Example
If I have 4 moles of a gas at a pressure of 5.6 atm and a volume of 12 L, what is the temperature of this gas?

12. Table Talk
If I have an unknown quantity of gas at a pressure of 1.2 atm, a volume of 31 L, and a temperature of 87 oC, how many moles of gas do I have?

13. Stop and Jot
If I contain 3 moles of gas in a container with a volume of 60 L and a temperature of 400 K, what is the pressure inside this container?

14. Summarize

15. Snake Game
We need to be able to do Ideal Gas Law Problems with relative quickness, therefore we are going to be doing the snake game to determine the answer to ideal gas law problems
You will be answering the problems alone
Many of the problems will require you to spot the error in the answer

16. Work Time

17. Question 1
If I have 4 moles of a gas at a pressure of 5.6 atm and a volume of 12 liters, what is the temperature? Remember R= (Lxatm)/(Kxmol)

18. Question 2
If I have an unknown quantity of gas at a pressure of 1.2 atm, a volume of 31 liters, and a temperature of 360 K, how many moles of gas do I have?

19. Question 3
If I contain 3 moles of gas in a container with a volume of 60 liters and at a temperature of 400 K, what is the pressure inside the container?

20. Question 4 Spot the error in this answer:
Problem – If I have moles of gas at a temperature of -200 oC and a pressure of 1.75 atmospheres, what is the volume of the gas?
Answer –

21. Question 5 Spot the error in this answer:
If four moles of a gas at a pressure of 5.4 atmospheres have a volume of 120 liters, what is the temperature?

22. Question 6 Spot the error in this answer:
If I have 72,000 mL of gas held at a pressure of 3.4 atm and a temperature of 225 K, how many moles of gas do I have?

23. Question 7
A weather ballon is filled with 150 L of helium at 23 oC and 1.00 atm. What volume does the balloon have when it has risen to a point in the atmosphere where the pressure is atm and the temperature is -31 oC?

24. Question 8
If I initially have a gas at a pressure of 12 atm, a volume of 23 liters, and a temperature of 200 K, and then I raise the pressure to 14 atm and increase the temperature to 300 K, what is the new volume of the gas?

25. Question 9
A gas takes up a volume of 17 liters, has a pressure of 2.3 atm, and a temperature of 299 K. If I raise the temperature to 350 K and lower the pressure to 1.5 atm, what is the new volume of the gas?

26. Question 10
A gas at 5 L and STP is increased to 5 atm and 500 K, what is the new pressure?

27. Question 11
If I have 17 liters of gas at a temperature of 67 0C and a pressure of atm, what will be the volume of the gas if I bring the gas to STP?

28. Question 12
You have a 15 moles of a gas at STP. What volume does this gas occupy?