1. Dalton’s Law of Partial Pressures A Tutorial Created By: Beth Dinich & Anne Kleinfeldt

2. What is it?  Dalton’s Law states that the pressure exerted by a mixture of gases equal the sum of the partial pressures of the gases in the mixture.

3. Check all of your units, they must be the same.  Lets start with checking and converting our pressures, if necessary.  Standard Pressures are as follows: 1atm 760mm or torrs 101.325kpa

4. Lets Try Converting  If we are given 92.1 kpa you must transfer it to atm using factor label.  Put your given pressure on the top and the standard pressure for the given units on the bottom.  The pressure that you are converting to will go as a standard pressure on the top of the given’s standard.

5. Let’s try some more  You are given 360 torrs and you need to change it to kpa.  You are given 1.73 atm and you need to convert it to mm.

6. Don’t forget your volumes!  All of your volume units must also be the same.  1 liter is 1000 ml.  1 ml is equal to 1 cm 3. Examples:  1.356 liters = 1356 ml = 1356 cm 3  5780 cm 3 = 5780 ml = 5.78 liters

7. The Equation P T = ∑ P X  The total pressure is equal to the summation of the partial pressures. P T = P A + P B + P C + …

8. Let’s Try One  P T =P A +P B +P C +P D  All of our pressures are in the same unit so we don’t about converting those. Our volume has one unit in liters and the rest in milliliters. We need to change it.  0.5 l = 500 ml OK, we are ready to start.

9. Here we go!  Now add all of your partial pressures together and you will have your total pressure.

10. Let’s try another!  You are given:

11. Work it out ! ! !  Don’t forget to convert all of your pressures and volumes to one unit of either pressure or volume, respectively.  Use your standard pressures and volumes to do this.  While working on this problem we decided to use atm for our pressure and ml for our volume.

12. Converting to the same units  Here we changed all of our pressures that were not in atm to atm. Don’t forget to have all of your volumes in the same units!

13. Let’s keep going …  Adding the partial pressures gives us the total pressure:

14. Here’s the quiz …  Grab a piece of scratch paper and begin.  Question number one.  What is Dalton’s Law of Partial Pressures?  Question number two.  What is the equation for Dalton’s Law of Partial Pressures?

15. Here’s the hard one …  Question number three.  What is the total pressure of the following?

16. Here are the answers...  Answer to question one.  Dalton’s law of partial pressures is the pressure exerted by a mixture of gasses equal to the sum of the partial pressures of the gases in the mixture.  Answer to question two.  P T = ∑ P X

17. Answer to Question Number Three...  152.7 kpa  How in the world do you get that???  The first thing you do is convert all of your pressures to kpa and volume to milliliters.

18. Here comes the rest...

19. Congratulations ! ! ! You Are DONE ! Congratulations ! ! ! You Are DONE !