1. Chapter 18 - Molecular Mixing 1 PS 101 Kim Cohn Email address Kcohn@academic.csubak.edu

2. Chapter 18 - Molecular Mixing 2 Comments- Chromatography If you used the same inks what could have been changed to get a better separation? Solvent (mobile phase) mixtures. Paper (stationary phase). Lengthen stationary phase.

3. Chapter 18 - Molecular Mixing 3 Comments- Chromatography Some chromatography: uses gas for the mobile phase, forces the liquid or gas through the stationary phase, or The purity of almost all drugs and many other substances is tested by chromatography.

4. Chapter 18 - Molecular Mixing 4 Comments- Chromatography DNA testing is done by chromatography. Good drug testing is done by chromatography. uses different stationary phase such as clay.

5. Chapter 18 - Molecular Mixing 5 Molecular Mixing Like dissolves like. Remember that when the two atoms are different one of the atoms may have more of the electron density than another. For example, HF. H  + - F  - The symbol  + means slightly positive.

6. Chapter 18 - Molecular Mixing 6 Molecular Mixing 2 The bond in H  + - F  - is called a polar bond. H 2 O also has polar bonds. Polar solvents will usually dissolve ionic compounds. H 2 O will dissolve NaCl. H 2 O will not dissolve olive oil or grease.

7. Chapter 18 - Molecular Mixing 7 Molecular Mixing 3 H 2 O has polar bonds. Polar solvents will usually dissolve ionic compounds. Polar solvents will usually dissolve other compounds that are polar, such as alcohol.

8. Chapter 18 - Molecular Mixing 8 Molecular Mixing 4 The bond in C-C is a non-polar bond. Gasoline is made of many different compounds all of which have non-polar bonds. Non-polar solvents will usually dissolve Non- polar compounds. Gasoline will not dissolve NaCl. Gasoline will dissolve olive oil or grease.

9. Chapter 18 - Molecular Mixing 9 Solutions Add sugar to water to form a homogeneous mixture called a solution. The sugar is the solute. Water is the solvent. Can have many different types of solutions.

10. Chapter 18 - Molecular Mixing 10 Solutions 2

11. Chapter 18 - Molecular Mixing 11 Solutions 3 Concentrated – No real meaning. Dilute – no real meaning. Saturated – The solvent holds as much solute as possible. Unsaturated. Insoluble – solute does not dissolve.

12. Chapter 18 - Molecular Mixing 12 Solutions 4 Amount of solute = ?

13. Chapter 18 - Molecular Mixing 13 Solutions 5 12 pencils is a pencils? 144 pencils is a of pencils? 500 sheets of paper is a ? 6.02 x 10 23 of anything is a Mole

14. Chapter 18 - Molecular Mixing 14 Solutions 6 Not this type of Mole

15. Chapter 18 - Molecular Mixing 15 Or this type of Mole

16. Chapter 18 - Molecular Mixing 16 Solutions 7 6.02 x 10 23 is a mole - 602,000,000,000,000,000,000 If you counted paper at the rate of one sheet per second it would take you 19,089,294,774,226,281 years to count a mole of paper. It is a big number because atoms are small.

17. Chapter 18 - Molecular Mixing 17 Solutions 8 A mole of sugar weighs about one half pound but contains how many molecules of sugar? 602,000,000,000,000,000,000 6.02 x 10 23 molecules. More about moles later.

18. Chapter 18 - Molecular Mixing 18 Solutions 9

19. Chapter 18 - Molecular Mixing 19 Question How many moles of sugar are there in 3.0 liters of a 0.5 M solution of sugar? A) 1.5 B) 3 C) 6 D) 0.166 E) None of the above

20. Chapter 18 - Molecular Mixing 20 Question If you need 1.5 moles of sugar how many liters of solution do you need to use if the solution is 0.5 M? A) 1.5 B) 3 C) 6 D) 0.166 E) None of the above

21. Chapter 18 - Molecular Mixing 21 Solubility Remember like dissolves like. The formula for ethanol, the alcohol we drink, is C 2 H 5 OH. The formula for water is HOH. Ethanol and water are soluble in each other.

22. Chapter 18 - Molecular Mixing 22 Cultural Interest The concentration units of liquor, wine and beer is proof. Proof is the concentration/2. 100 proof alcohol is 50% ethanol. 1 glass beer = 1 glass wine = 1 mixed drink. Legally drunk is 2 drinks/hour for a 150 pound man. Or about 1.5 drinks/hour for the same weight of woman.

23. Chapter 18 - Molecular Mixing 23 Solubility 2 Sugar contains many OH bonds. It will also dissolve in water. About 200 g of sugar will dissolve in 100 mLs of water. Oxygen, a gas, contains no OH bonds and is not very soluble in water. About 0.004 g of O 2 will dissolve in water.

24. Chapter 18 - Molecular Mixing 24 Solubility 3 The solubility of a solid will usually go up as the temperature goes up. The solubility of a gas will always go down as the temperature goes up. The solubility of a gas will always go up as the pressure goes up. What happens when you open a can of soda?

25. Chapter 18 - Molecular Mixing 25 Soap

26. Chapter 18 - Molecular Mixing 26 Soap 2

27. Chapter 18 - Molecular Mixing 27 Hard Water Contains the dissolved salts of iron (Fe 2+ ), calcium (Ca 2+ ) or magnesium (Mg 2+ ). These ions form a precipitate with soap. Squeaky clean?? I don’t think so.

28. Chapter 18 - Molecular Mixing 28 Hard Water 2 Can add Na 2 CO 3, sodium carbonate or washing soda, to hard water. These ions form a precipitate with the Ca 2+ ions. Can call the Culligan man and replace the Ca 2+ ions with Na + ions. Watch out if you have high blood pressure.

29. Chapter 18 - Molecular Mixing 29 Capillary action

30. Chapter 18 - Molecular Mixing 30 Capillary action 2

31. Chapter 18 - Molecular Mixing 31 Capillary Action 3 It takes more energy to break through the surface of water than move through the bulk of the liquid. This is why bugs can skate along the surface of the water. Or, if you are careful, you can “float” a paper clip on water.

32. Chapter 18 - Molecular Mixing 32 Capillary Action 4 You can reduce the surface tension by adding soap to water. Because of surface tension water will creep up small tubes. Surface tension is important in bringing water up in plants. You can drown a duck by reducing the surface tension of the water a duck swims in.