1. Natural Sciences Grade 7
Term 2: Matter & Materials
Separating mixtures
(ppt 1)

2. Topic 2 Separating mixtures
Natural Sciences - Grade 7

3. Mixtures [substances]
Examples of pure substances:
Gold particles
Gold nuggets
Water particles (all the particles in a glass of
water are the same).
Table salt particles (all the particles in a spoon of
table salt are arranged the same way)
Mixtures can be:
- combined as solutions, suspensions or colloids.
- homogeneous [the make up is uniform and every constituent of the mixture has the same properties –e.g. air]
- heterogeneous [the different components are visible because different phases are taking place among the parts – e.g. sand and water; sand
and iron filings; rock water and oil; gold powder and silver powder; etc.]
- Mixtures may be classified into 4 divisions: Suspensions, Colloids, Emulsions, and Alloys * Suspensions:  mixtures where one chemical substance is dispersed in the other and can be observed as standing particles when left
undisturbed *Colloids:  heterogeneous systems in which one substance is dispersed as very fine particles in the other substance called the dispersion medium * Emulsions:  colloidal systems whose dispersed phase and dispersion medium are both in the liquid state * Alloys:  homogeneous mixtures of metal elements whose proportions of combination are often fixed. Read more: Facts about mixtures | Interesting Facts 
Natural Sciences - Grade 7

4. Natural Sciences - Grade 7
Mixtures [particles]
Mixtures can be:
- combined as solutions, suspensions or colloids.
- homogeneous [the make up is uniform and every constituent of the mixture has the same properties –e.g. air]
- heterogeneous [the different components are visible because different phases are taking place among the parts – e.g. sand and water; sand
and iron filings; rock water and oil; gold powder and silver powder; etc.]
- Mixtures may be classified into 4 divisions: Suspensions, Colloids, Emulsions, and Alloys * Suspensions:  mixtures where one chemical substance is dispersed in the other and can be observed as standing particles when left
undisturbed *Colloids:  heterogeneous systems in which one substance is dispersed as very fine particles in the other substance called the dispersion medium * Emulsions:  colloidal systems whose dispersed phase and dispersion medium are both in the liquid state * Alloys:  homogeneous mixtures of metal elements whose proportions of combination are often fixed. Read more: Facts about mixtures | Interesting Facts 
Natural Sciences - Grade 7

5. Natural Sciences - Grade 7
Mixtures [examples]
A mixture is made up of 2 or more materials or Substances, which have different physical properties. Sea water mixture of water and salt; Brass mixture of zinc and copper; Air mixture of gases [oxygen; nitrogen; carbon dioxide] Concrete mixture of cement, water, sand and lime.
Mixtures can be:
- combined as solutions, suspensions or colloids.
- homogeneous [the make up is uniform and every constituent of the mixture has the same properties –e.g. air]
- heterogeneous [the different components are visible because different phases are taking place among the parts – e.g. sand and water; sand and iron
filings; rock water and oil; gold powder and silver powder; etc.]
- Mixtures may be classified into 4 divisions: Suspensions, Colloids, Emulsions, and Alloys * Suspensions:  mixtures where one chemical substance is dispersed in the other and can be observed as standing particles when left
undisturbed *Colloids:  heterogeneous systems in which one substance is dispersed as very fine particles in the other substance called the dispersion medium * Emulsions:  colloidal systems whose dispersed phase and dispersion medium are both in the liquid state * Alloys:  homogeneous mixtures of metal elements whose proportions of combination are often fixed. Read more: Facts about mixtures | Interesting Facts 
Natural Sciences - Grade 7

6. Natural Sciences - Grade 7
Mixtures [solutions]
A mixture of a solid dissolved in a liquid is called a solution.
Natural Sciences - Grade 7

7. Mixtures [physical properties]
The parts of a mixture have different physical properties:
The substances of beans and rice, as well as fruit salad that are mixed, keep all of their own physical properties.
Different mixture parts do not join together, but it can be combined in any amounts.
Natural Sciences - Grade 7

8. Natural Sciences - Grade 7
Mixtures [examples]
Practical: let the learners mix rice and dry beans / samp and sugar beans / macaroni and lentils, etc. Then they must sort it again.
Natural Sciences - Grade 7

9. Mixtures [combination of properties]
The particles of one substance move in between the particles of the other substance when the two are mixed.
Salt water looks like water, but it tastes like salt
(It is a combination of the properties of the
substances that are mixed).
Natural Sciences - Grade 7