1. Natural Sciences and Technology Grade 6
Term 2: Matter and Materials
Dissolving

2. Factors that affect the rate of dissolving
Topic 4 Dissolving
Factors that affect the rate of dissolving
Gr 6 Natural Sciences and Technology – Term 2, Topic 4

3. What is the difference between melting and dissolving?
Do you remember the difference between melting and dissolving?
Melting is ...
Dissolving is ...
Ask learners if they remember the differences between melting and dissolving
Gr 6 Natural Sciences and Technology – Term 2, Topic 4

4. Are melting and dissolving the same thing?
No. These are two different processes.
MELTING – through an increase in temperature the particles of the material are freed up and move around and once they have cooled down again, they reform into a different shape.
DISSOLVING- the particles (solute) break up and become evenly spread throughout the solvent to form a solution.
NOTE : The solids that dissolve DO NOT
DISAPPEAR, their particles spread out.
Use this slide to briefly remind learners about the difference between melting and dissolving
Gr 6 Natural Sciences and Technology – Term 2, Topic 4

5. Rates of dissolving
Factors that affect the rate (time taken) for a solute to dissolve in a mixture include:
- the temperature of the mixture;
- stirring or shaking the mixture;
- the grain or size of the solute.
Gr 6 Natural Sciences and Technology – Term 2, Topic 4

6. Graph showing how temperature affects rate of dissolving

7. Graph showing how stirring affects rate of dissolving
Gr 6 Natural Sciences and Technology – Term 2, Topic 4

8. Graph showing how grain size affects rate of dissolving