Mixtures

1. Mixtures Pgs 62 - 69

2. Properties of Mixtures A mixture is a combination of two or more substances that are not chemically combined. Two or more substances form a mixture as long as they do not react to form a compound. Ex. Cheese and tomato sauce.

3. Substances within Mixtures Each substance within a mixture has the same chemical makeup before it forms a mixture. Sometimes you can see the different substances, sometimes you cannot. Ex. Pizza, salt water

4. Separation of Mixtures You can remove items of a mixture because they did not combine chemically. Ex. Mushrooms on a pizza. Not all mixtures are easy to separate though. You may need a special technique. Ex. Distillation, magnet, centrifuge, evaporation, or multiple steps .

6. No Definite Ratio Unlike compounds, mixtures do not have a specific mass ratio in which they exist. Ex. Granite can have different ratios of the minerals that make it up, like feldspar or quarts, but it is still granite. Air is a mixture of gases. Sometimes there is more water vapor in the air than other days, but it is still air.

7. Mixture vs. Compounds Mixtures Compounds Components are elements, compounds, or both. Components keep their original properties Separated by physical means. Formed using any ratio of components. Components are elements. Components lose their original properties. Separated by chemical means. Formed using a set mass ratio of components.

8. Solutions A solution is a mixture that appears to be a single substance but is composed of particles of two or more substances that are evenly distributed amongst each other. They are also called homogenous mixtures. Solute the substance that is dissolved. Solvent the substance the solute is dissolved in. Ex. Salt water (salt is the solute, water is the solvent)

9. Other Solutions Mineral water, soft drinks and gasoline are all liquid solutions. Alloys are solid solutions of metals or nonmetals. Ex. Brass is a solution of zinc and copper. Steel is an alloy of carbon and iron. Other examples are dry air, soft drinks, antifreeze, sugar water, brass.

10. Particles in Solutions Particles in solutions are so small they cannot be filtered out. They cannot even scatter light. Some solutions can look like compounds even though they are not.

11. Concentration The amount of solute dissolved in a solvent is concentration. Knowing exact amounts of concentration is important in chemistry and medicine. Solutions can be described as concentrated or dilute, however these are terms that do not describe specific amounts. A solution that contains all the solute it can hold at a given temperature is considered saturated.

12. Solubility The solubility of a solute is the amount of solute needed to make a saturated solution using a given amount of solvent at a certain temperature. Solubility is expressed in grams of solute per 100ml of solvent. Solubility of gases in liquids decreases with temperature. Solubility of solids in liquids increases with temperature.

13. How Quickly Solids Dissolve in Liquids • Several factors affect how fast the solid will dissolve. • Mixing increases rate of dissolving. • Heating increases the rate of dissolving. • Crushing increases the rate of dissolving.

14. Suspensions A mixture in which particles of a material are dispersed throughout a liquid or gas but are large enough that they settle out is a suspension. Ex. Snow globe, muddy water, Italian dressing. Suspensions are heterogeneous mixtures. Particles are large enough to be seen and can be separated by using a filter.

15. Colloids A mixture in which the particles are dispersed throughout, but are not heavy enough to settle out is a colloid. Particles of a colloids are fairly small and well mixed. Ex. Milk, mayonnaise, stick deodorant, jello, whip cream, and fog. Colloids cannot be separated by filtration and the particles are large enough to scatter light.