1. HONORS CHEMISTRY
May 6, 2014

2. Brain Teaser Rationalize the following observations.
A thin-walled can will collapse when the air inside is removed by a vacuum pump.
Aerosol cans will explode if heated

3. Agenda
Brain Teaser
Notes: Combined Gas law, Avogadro’s Law and Ideal Gas Law
Homework
Combined Gas Law Worksheet
Questions 2,4,6,8
Ideal Gas Law Worksheet
Questions 1,2,4,6

4. Combined Gas Law
Boyle’s Law
Charles’s
Combined

5. Avogadro’s Law
How can we change the volume of a gas in a balloon?

6. Avogadro’s Law
Why did the blimp deflate?

7. Avogadro’s Law
If the pressure and temperature are held constant, the volume of a gas is directly proportional to the number of moles (n). V n

8. Gas Laws Part 2: Work on Gas Notes Sheet instead of Brain Teaser Avogadro’s Law
O2  O3
Suppose we have a 12.2 L sample containing 0.50 mol oxygen gas at a pressure of 1 atm and a temperature of 25 ºC.
1) Balance the equation
2) If all this oxygen is converted to ozone at the same
temperature and pressure, what would be the volume
of the ozone?

9. Dalton's Law
The total pressure is the sum of the partial pressures.
Ptotal = P1 + P2 + P3 + …..

10. Dalton’s Law Practice
A mixture of oxygen, carbon dioxide, and nitrogen has a total pressure of 0.97atm. What is the partial pressure of Oxygen, if the partial pressure of carbon dioxide is 0.70atm and the partial pressure of nitrogen is 0.12atm?

11. The Gas Laws Variables: V, P, T, n (or m and MM or d)
Ideal Gas: properties are independent of the identity of the gas
What is the relationship between the variables for an ideal gas?
Basketball
Bike Tire

12. 5.3 Ideal Gas Law PV = nRT P= pressure (atm) V = volume (L)
n = number of moles
R = ideal gas constant
L·atm/mol·K
T = temperature (K)

13. STP Standard Temperature and Pressure
0ºC and 1 atm
Use the Ideal Gas Law to calculate the volume of 1.00 mol of gas at STP

14. Molar Volume at STP
We can show that L of any gas at 0C and 1 atm contain 6.02  1023 gas molecules.

15. Example
A sample of Hydrogen gas has a volume of 8.56 L at 0ºC and a pressure of 1.5 atm. Calculate the moles H2 molecules present in this gas sample.

16. Practice Problem
The volume of an oxygen cylinder is 1.85 L. What mass of oxygen gas remains in the cylinder when it is “empty” if the pressure is 755 torr and the temperature is 18.1oC?
Answer: 2.46 g