1. 1 Mixtures Day 1: Chapter 14 Lake Nyos, Cameroon Courtesy of George Kling, page 556-557

2. Mixture 2 or more substances 2 or more substances physically physically combined. combined.

3. Two Types: Homogeneous Homogeneous Same throughout Heterogeneous Heterogeneous Different throughout

4. Homogeneous? Homogeneous? Heterogeneous? Heterogeneous? Mixture

5. Heterogeneous Mixtures Suspension: two or more substances that do NOT mix Insoluble

6. Suspensions a mixture appears a mixture appears uniform when shaken. uniform when shaken. Particles Settle out Particles Settle out Need to shake or stir Need to shake or stir Ex. orange juice, salad dressing Ex. orange juice, salad dressing

8. SUSPENSION

9. WHY? “LIKES DISSOLVES LIKES” Polar AND Nonpolar : NOT MIX - Two substances only go together if they are alike. If they aren’t alike NOT go together. - Ex. Wax (nonpolar) and water (polar)

10. Polarity A molecule is polar when electrons are shared unequally. Have a (+) and (-) end A molecule is polar when electrons are shared unequally. Have a (+) and (-) end Molecules are nonpolar when electrons are shared equally between atoms Molecules are nonpolar when electrons are shared equally between atoms Water is very polar Water is very polar

11. Solution: Homogeneous Mixtures homogeneous mixture of 2 or more substances uniformly spread throughout a medium. homogeneous mixture of 2 or more substances uniformly spread throughout a medium.

12. 12 Some Definitions A solution is a HOMOGENEOUS mixture of 2 or more substances in a single phase. One constituent is usually regarded as the SOLVENT and the others as SOLUTES.

13. Why Mix Uniformly? “Likes dissolve likes” “Likes dissolve likes” D6 C30 D6 C30 Polar dissolves in polar or Nonpolar dissolves in nonpolar Uses: dry cleaning

14. Microscopic Composition Demo: ethanol/water Demo: ethanol/water

15. 15Colloid

16. Colloid Many types: we will look at one EMULSIONS Do not settle out or dissolve HOMOGENEOUS, HOMOGENEOUS, Opaque, not let light through

17. Likes Dissolve Likes How do we get two thing that are NOT alike to go together? How do we get two thing that are NOT alike to go together? Need Emulsifying Agent = third ingredient Need Emulsifying Agent = third ingredient Emulsifying agent is BOTH polar and nonpolar Emulsifying agent is BOTH polar and nonpolar

18. 3. Emulsion a mixture where polar a mixture where polar substance is forced to mix uniformly with a nonpolar substance substance is forced to mix uniformly with a nonpolar substance Held together by emulsifying agent Held together by emulsifying agent Ex. mayonnaise, glue Ex. mayonnaise, glue

19. EMULSION

20. EMULSIFING AGENT Disk 10: Chapter 20 SOAPS AND DETERGENTS

21. SolutionsEmulsions(Colloid)Suspension UniformHomogeneous Don’t Settle out “Shake”Heterogeneous Transparent Light through Scatters Light Opaque Two or more phases Solute and solvent Alike (p/p or n/n) Emulsifying Agent Polar and nonpolar Polar with nonpolar LETS COMPARE mixtures

22. Mixture Properties & Particle Size Dispersed particles too big = suspension Dispersed particles too big = suspension Can filter out Dispersed particles small = solution Dispersed particles small = solution Pass through membrane

23. NoneTyndalleffectTyndalleffect 0.1 -1 nm Atoms, ions Small cules 1-200 nm Largemolecules > 200nm Pass through Do NOT Pass through Throughmembrane Do NOT Pass through Do NOT Do NOT Pass through LIGHT SCATTERING PARTICLE SIZE FILTRATION DIALYSIS PropertySolutions Emulsions(Colloid) Suspension