1. MIXTURES, SOLUTIONS AND PURE SUBSTANCES

2. Matter and its appearance  According to its appearance, there are two kinds of material systems:  Homogeneous systems: they have the same properties and compositions in all different parts of them.  Heterogeneous systems: different parts with different properties can be found in them.

3. Homogeneous Systems

4. Heterogeneous Systems

5. Heterogeneous Mixtures  Systems with several different substances that can be distinguished:  Oil and water.  Granite is a rock that has three different substances: quartz, mica and felspar.  Blood: using a microscope we can see a liquid (plasma) and different kinds of cells.  Smoke: has solid particles in a gas (air).

6. Heterogeneous Mixtures  How to separate their components: – If the components are a solid and a liquid, we can separate them by filtering. E. g.: water and sand

7. Heterogeneous Mixtures  How to separate their components: – Decantation: This method uses the different densities of the components to separate them: (E.g.: oil and water)

8. Homogeneous Systems There are two kinds of homogeneous systems: Pure substances: They have only one component They have constant composition and properties. Solutions: They have several components. Their composition can be changed

9. Solutions A solution has, at least, two components: Solute: It is the component that is present in a lower quantity in the solution. Solvent: It is the component that is present in excess. Its state never changes when the solution is being formed A simple sample: salty water: There is much more water than salt Water is a liquid and the solution too. SOLUTE = SALT and SOLVENT = WATER

10. Solutions They are not always liquids !!!

11. Solutions How to separate its components: – Evaporation and crystallization: a liquid evaporates at room temperature, but a solid doesn't.

12. Solutions How to separate its components: – Distillation: this method is useful to separate: Liquids whose boiling points are different Liquids and solids

13. Pure Substances Pure substances: They have a constant composition. They can't be separated in simpler substances using physical methods. There are two different kinds of pure substances: Chemical compounds: pure substances that cannot be separated using chemical methods. Elements: pure substances that can't be separated into others

14. Four kinds of matter