Mixtures and Solutions

1. Mixtures and Solutions Science 2nd Nine Weeks

2. Mixtures

3. What are Mixtures? • A mixture is a physical combination of substances • The substances remain the same even though they are close together • You can separate mixtures back into their original substances

4. Types of Mixtures- Heterogeneous • Heterogeneous mixtures have different parts you can plainly see (snack mix) • Not all heterogeneous mixtures look “speckled” or “chunky”; they may look smooth or creamy • However, if you look at them under a microscope you can see the different parts clearly (suspension) • Over time more and more parts of the suspension will settle to the bottom (mud in a stream) • Stirring or shaking the mixture will make it look smooth again • “Shake well before using”

5. Types of Mixtures-heterogeneous continued • Colloids are mixtures that are like suspensions but their particles do not settle • They make the mixture look cloudy or creamy • Examples: smoke, mayonnaise, and foam

6. Types of mixtures- Homogeneous (Mixtures) • A homogeneous mixture may be called a solution • A solution is a mixture with parts that blend so that it looks the same everywhere even under a microscope • The smaller amount dissolved in a solution is called the solute • The larger amount that dissolves the other substance in a solution is called a solvent • In sugar water, sugar is the solute and water is the solvent • Solutions can be made with solids, liquids, and gases • Examples of solutions: window cleaner, bleach, vinegar, and beverages

7. solubility • The maximum amount of a solute that can dissolve in a solvent is called solubility • Solubility often depends on temperature; many substances (not all) become more soluble at higher temperatures • Water is often called the universal solvent because it can dissolve many things

8. How can mixtures be separated? • Parts of a mixture can be separated by physical methods • These physical methods separate the parts of a mixture without changing their properties or identities • Properties such as density, solubility, particle size, magnetism, and boiling point are used to separate mixtures

9. How can mixtures be separated?- magnetism • A magnet separates iron fillings from nonmagnetic materials

10. How can mixtures be separated?- sifting • A sieve separates materials of different sizes.

11. How can mixtures be separated?- filtration • When water is added to salt and sand, the salt dissolves, but the sand does not. A filter separates the sand from the salt water.

12. How can mixtures be separated?- flotation • The wood chips float to the top of the water, and the rocks settle at the bottom. The wood chips can be skimmed off and allowed to dry.

13. How can mixtures be separated?-Evaporation • Water evaporates from salt water, leaving the salt behind.

14. What is distillation? • Separates the parts of a mixture by vaporization and condensation • This can be done to separate a solution of water and salt • The water, with the lowest boiling point, will boil first, change to a gas and leave the container • The salt will remain • The gas is condensed into a cooling tube and can flow into another container • The parts of the mixture are completely separated