There are 8 questions total. Gas Problems? How about gas LAW problems? Take out a piece of lined paper and answer the numbered questions with a yellow star by them. The answers are behind the colored circles in each slide. There are 8 questions total.

Charles’ Law Constants are Variables are Direct relationship # of particles Pressure Variables are Temperature Volume Direct relationship Equation is: V1 = V2 T1 T2

Boyle’s Law Constants are Variables are Indirect relationship # of particles Temperature Variables are Pressure Volume Indirect relationship Equation is: P1V1 = P2V2

GayLussac’s Law Constants are Variables are Direct relationship # of particles Pressure Variables are Temperature Volume Direct relationship Equation is: P1 = P2 T1 = T2

Standard Temperature & Pressure (STP) There are standard values for temperature and pressure The reason is that it creates consistent conditions for scientists to compare their results. Standard Temperature 0°C (K = 273 + °C  273K) Standard Pressure: The following are equivalent 1 atm = 760 torr = 760 mm Hg Standard Volume: 22.4L in a mole of any gas at STP

MIXED PROBLEM PRACTICE Do the following steps for EACH problem Identify the law needed to solve the problem (Charle’s, Boyle’s, Gay-Lussac’s) Identify whether it’s a direct or inverse relationship Solve the problem

1. A gas at 45°C and 1. 2 atm is cooled to a temperature of 5°C *1. A gas at 45°C and 1.2 atm is cooled to a temperature of 5°C. What is the new pressure of the gas? Set this up and work it before you check it on the next slide. T1 = T2 = P1 = P2 = ?

*2. A 2.3L sample of gas under 500 torr of pressure is allowed to expand with a final pressure of 2.3 atm. What is the final volume? **Notice both torr and atm are used so multiply the 2.3 by 760 torr using factor label… V1 = V2 = ? P1 = P2 =

*3. A gas at a pressure of 700 torr is pressurized to 1200 torr and 50°C. What was the initial temperature of the gas in degrees Celsius – You will get your answer and then subtract 273 to go from K to °C? You will need to find it in Kelvin first. T1 = ? T2 = P1 = P2 =

*4. A syringe containing 5.5 mL of gas at standard temperature is allowed to expand to twice its volume. What is the final temperature? What is twice the 5.5mL? V1 = V2 = T1 = T2 = ?

*5. 15.0L of a gas at standard pressure is shrunk to a volume of 12.5L. What is the new pressure, in torr? V1 = V2 = P1 = P2 = ?

The combined gas law: If all three of these variables P, V and T are changed in a new set of conditions (for instance STP) and 5 of the six variables are known, the sixth can be calculated using….THE COMBINED GAS LAW P1V1 = P2V2 T1 T2

6. How would the pressure of 11. 2 L of gas at STP change in a 10 *6. How would the pressure of 11.2 L of gas at STP change in a 10.0L container at 298K?

7. What is the initial pressure in a 15. 0L tank at 40 *7. What is the initial pressure in a 15.0L tank at 40.0 C that contained 2550L of propane (C3H8) at STP? – (This is a problem to grill out in the parking lot on a warm spring day!)

8. Calculate the volume of a gas at STP that occupies 255mL at 2 *8. Calculate the volume of a gas at STP that occupies 255mL at 2.2 atm in a lab that is 25.5 degrees C.