1. Differences between pure substances and mixtures

2. Characteristics of Pure Substances
What does this mean?
Fixed composition
Distinct properties
Cannot be separated into simpler substances by physical methods
Can only be changed in identity and properties by chemical methods (Unit 4)
Properties do not vary one sample to another sample
Instructional Approach(s): The teacher should present the information on the slide while the students record the important information on their graphic organizer.

3. Mixtures Form when elements and/or compounds are combined physically
Properties of a mixture are related to its components
Composition varies from sample to sample
Can be separated by physical methods
Examples of Mixtures: Tea, Perfume, Air, Salad, Beach sand, oil and vinegar salad dressing, etc.
Instructional Approach(s): The teacher should present the information on the slide while the students record the important information on their graphic organizer

4. Solutions:
water and ……

5. How can we distinguish between a pure substance and an homogeneus mixture?

6. How can we distinguish between a pure substance and an homogeneus mixture?
If pure water is heated until it boils, we will observe that temperature remains constant at 100 ºC during the change of state.
However when water is not pure the temperature will increase progressively.

7. What are differences and similarities between a pure substance and a homogeneous mixture?
Pure substances
Homogeneous Mixtures
Consists of a single type of substance
It is a system that consists of two or more pure substances
Cannot be separated into other substances by physical methods.
Can be separated into its components by physical methods (distillation, evaporation, chromatography..)
Has its own fixed specific properties (density, boiling point, …)
Mixtures shows the properties of its components and these properties change with the proportion of the components (concentration)
Temperature is constant when boiling.
Temperature changes when boiling, the boiling point is unclear.
Examples: iron, copper, water, sodium chlorine, copper sulfate,
Examples: sea water, air, sugar in water
BOTH ARE HOMOGENEOUS

8. Learning more What would you do? Do you drink chemically pure H2O?
What is the difference between chemically pure versus “Clean” water?

9. Watching videos UNICEF Tap project
How far would you walk to find clean drinking water?

10. Working in groups What's the difference between salt and fresh water?
What would you do to differentiate them?

11. Your ideas