1. Chapter 13: Section 1 What is a Solution?

2. Mixtures mixture (def)- a combination of 2 or more substances that are not chemically combined there are 2 types of mixtures: –homogeneous (def)- a mixture with a uniform composition; also called a solution –heterogeneous (def)- a non-uniform mixture of dissimilar components

3. Solutions solution (def)- a stable homogeneous mixture of 2 or more substances uniformly dispersed throughout a single phase particles are evenly distributed particles are so small they can not be seen or filtered out

4. Solutions (cont.) solutions are transparent (they may have color, but they are still transparent; light passes through them) term is usually used to describe a homogeneous liquid mixture (but gas and solid solutions also exist)

5. Solutions (cont.) solvent (def)- the substance in which the solute is dissolved; usually the primary ingredient solute (def)- the substance that is dissolved in the solvent; usually the secondary ingredient(s) in the solution

6. Solutions (cont.) examples: gasoline, air and sweetened tea solutions in which water is the solvent are called aqueous solutions

7. Suspensions suspension (def)- a mixture in which particles of a material are dispersed throughout a liquid or gas suspensions are temporary heterogeneous mixtures particles are fairly large (>1000nm) and many times can be seen with the naked eye mixed particles are “broken up” or suspended, but not dissolved together

8. Suspensions (cont.) over time, suspensions may separate or “settle out” suspensions can be separated by filtering suspensions are milky or opaque; they do not transmit light examples: blood, aerosol sprays

9. Colloids colloid (def)- a mixture consisting of tiny particles that are intermediate in size between those of a solution and a suspension particle size is between 2 to 1000 nm colloids are stable heterogeneous mixtures they do not generally separate on standing and can not be filtered apart

10. Colloids (cont.) examples: fog, milk, jelly, colloids frequently appear murky and the particles are large enough to scatter light (example: headlight beam scattered by fog)

11. Separating Mixtures physical methods can be used to separate mixtures the method of separation depends on the type of mixture

12. General methods to Separate Mixtures: homogeneous mixtures (solutions) –evaporation –distillation heterogeneous mixtures –settling out/decanting (suspensions) –filtering (suspensions) –centrifuging (suspensions and colloids)

13. Chromatography can be used to separate mixtures by differences in attraction. how it works: the material to be separated is dissolved in a mobile phase (solvent) the dissolved molecules move along a solid phase particles that move more slowly are attracted more strongly to the solid phase

14. example: paper chromotography material to be separated: ink mobile phase: solvent such as alcohol or water solid phase: filter or blotter paper process: the solvent dissolves the ink as it travels up the paper explanation: the slower the dyes move (separate) the more they are attracted to the paper result: the ink will be separated into the individual dyes (colors) that compose it [see figure 6 page 458]

15. Distillation separates mixtures based on differences in their boiling points. if the boiling points of the mixture’s components are different, they can be separated by distillation as each successive component reaches its boiling point, it can be evaporated off and allowed to recondense and be collected into separate distillates

16. Distillation (cont.) example: sea water can be distilled to produce fresh water as a distillate distillation is also used to separate crude oil the first distillates (lowest boiling points) are used to produce plastics next, in order: gasoline, diesel fuel, heating oil and then kerosene