1. Chapter 13 Solutions

2. Pure vs. Mixtures PURE SUBSTANCE MIXTURES sample of matter  single element or single compound Definite chemical and physical properties Boiling point/ melting point Density Sample of matter  two or more pure substances Not chemically combined

3. Different Types of Mixtures • Heterogeneous • Large enough to see under a microscope • Uneven distribution • Homogeneous • Particles are molecule sized • Appears to be evenly distributed

4. Heterogeneous Mixtures • Suspension • Temporary heterogeneous mixture • Different parts separate over time

5. SOLUTIONS • Homogeneous mixtures consisting of two parts • Solute • The substance that is being dissolved • Solvent • The substance that is “DOING” the dissolving • Universal Solvent  water

6. Solutions Definitions • Solution - homogeneous mixture Solute - substance being dissolved Solvent - present in greater amount (the substance that dissolves the solute)

7. Colloids • Stable heterogeneous mixture • Particles are much larger than the solute, but small enough that they will not settle out over time • Scatters light

8. Mixtures Classified by Particle Size Solution: Homogeneous mixture; solute does not separate on standing; Solute particle size = .01 – 1 nm e.g., saltwater Colloid: Heterogeneous mixture; solute does not separate on standing; Solute particle size = 1 – 1000 nm, cannot be separated by filtration, but will scatter light e.g., milk, cheese, butter, shaving cream Suspension: Appears uniform while being stirred, but settles over time. Solute particle size > 1000nm, can be separated by filtration e. g., dirt and water, sand and water

9. Separating Mixtures • Separating mixtures in dependent upon the physical properties of the pure substance in the mixture • Decanting • Centrifuge • Filtration • Distillation • Evaporation • Chromatography

10. Separating Mixtures Decanting Centrifuge Properties of the Mixture A “liquid” and a “solid” We did this in the copper/ silver lab Pour the liquid from off the top of the solid. Properties of the mixture Separated based on densities The denser substance collects at the bottom as it spins.

11. Separating Mixtures Filtration Evaporation Properties of Mixtures Separates soluble and insoluble substances Liquid vs Solid Properties of mixtures Heat water to separate a soluble or insoluble particles in the mixture Used to obtain a solute from a solution

12. Separating Mixtures Distillation Properties of Mixture Separated based on the varying boiling points of the substances in the mixture Substance with a lower boiling point with evaporate and then if allowed to cool and condense they can be collected

13. Chromatography • Another way to separate very complex mixtures • Ink in your markers  Is it a mixture or pure substance??

14. How does chromatography work? • Can be used with any substance that reacts or bonds with the paper being used • Separated based on how quickly it dissolves • Color dyes • Solvent moves up the paper by capillary action • When solvent hits the sample it will dissolve it

15. Then what??? • Different compounds will travel at different rates • Meaning they will stop while others will keep going • They will travel at different rates due to solubility differences and the difference in attraction to the paper