1. Grade 7 Science
Solutions

2. Solutions… a review A homogeneous mixture They appear as ONE substance
Examples: tap water, vinegar, gold jewelry

3. We will learn:
identify the solute and the solvent in a variety of solutions
distinguish between soluble and insoluble substances
describe the concentration and solubility of substances qualitatively and quantitatively

4. Solutions have 2 parts: Solute Solvent
The substance that dissolves (found in less amounts)
Solvent
The substance in which the solute dissolves (found in the greatest amounts)

5. Solute= Salt in this case
Solvent= Water

6. Page 255: Solute or Solvent?
A. Brass is used to make many objects. Brass is a solution of zinc metal in a copper metal.
B. Hydrogen peroxide is used to disinfect cuts. Hydrogen peroxide is a solution of 3% hydrogen and 97% water.

7. Solute or Solvent?
C. Dental amalgam is a metal that is used to fill cavities. It is a solution of mercury in tin.
D. Deicing fluid is a cleaner used to clean car and truck windshields. It is made up of a solution of propylene glycol in water.

8. Solutions song. - Journey with Me. http://www. youtube. com/watch

9. Dissolving...
To mix completely (the solute dissolves into the solvent.)
Some substances are able to dissolve better than others.

10. For those about to dissolve- we solute you!

11. How are substances soluble?
The Particle Theory of Matter states that “there are attractive forces between the particles”.

12. This means that the solute is soluble in that solvent.
In order to dissolve, the particles must be more strongly attracted to the particles of the solvent than to themselves.
This means that the solute is soluble in that solvent.

13. If something is ABLE to dissolve then it is soluble.
For example, sugar dissolves in water.

14. Particle Theory- Dissolving animation

15. How are substances insoluble?
If the particles of the solute are more attracted to their own particles than the solvent particles, dissolving does NOT occur. The solute is said to be insoluble in that solvent. (ie. Mechanical)

16. If something is UNABLE to dissolve then it is insoluble.
For example, sand does not dissolve in water.

18. Soluble or Insoluble?
soluble
insoluble

19. Solvent or Not?
Some materials are good solvents for some solutes but not others. For example, oil is insoluble in water but soluble in gasoline.

20. Gas Gas Air Solute: oxygen, carbon dioxide, other gases
States of Solutes and Solvents- Put book and workbook away. Hand out exit cards. Below is an example!
Air
Solute: oxygen, carbon dioxide, other gases
Solvent: nitrogen (most of our air is actually Nitrogen!!)
Gas
Gas

21. Soda:
(a combination of carbon dioxide in water). Identify water or carbon dioxide as the solute/solvent and say which state they are.
Solute: ?
Solvent: ?
State of Solute: ?
State of Solvent: ?

22. Vinegar:
(a combination of 3% acetic acid and 97% water). Identify water or acetic acid as the solute/solvent and say which state they are.
Solute: ?
Solvent: ?
State of Solute: ?
State of Solvent: ?

23. Filtered Sea Water:
(salt in water). Identify water or salt as the solute/solvent and say which state they are.
Solute: ?
Solvent: ?
State of Solute: ?
State of Solvent: ?

24. Brass
(an alloy of a zinc metal in a copper metal) Identify zinc or copper as the solute/solvent and say which state they are.
Solute:?
Solvent: ?
State of Solute: ?
State of Solvent: ?

25. Concentrations of Solutions
Grade 7 Science
Concentrations of Solutions

26. Concentration (p 4 of workbook; 264)
The two cups below each had hot water with a tea
bag sitting in them. The time below the cup
indicates how long the tea bag has been in the cup.
10 minutes minutes

27. Concentration is…
The quantity of solute that is dissolved in a certain quantity of the solvent.
Can be described qualitatively or quantitatively.

28. Qualitative:
Using words such as like “dilute” or
“concentrated”

29. Quantitative:
Using numbers. This is especially important when safety is an issue!

30. Student Activity… 1. Demo of qualitative concentration
2. Demo of quantitative concentration

31. Student Practice… Quantitative?
#1(a). Food coloring made the water blue.
(b). Adding 3 mL of food coloring turned 250 mL of water blue.
Qualitative
Quantitative

32. #2(a). The water became warmer.
(b). The water’s temperature increased by 5 degree Celsius.
Qualitative
Quantitative

33. #3(a). We needed just over a dozen floor tiles for our model room.
(b). We needed 14 floor tiles for our model room.
Qualitative
Quantitative

34. #4(a). The liquid boiled in 5 min.
(b). The liquid took only a few minutes to boil.
Quantitative
Qualitative

35. #5(a). The mass of this solid is 5g more than that one.
(b). This solid is heavier than that one.
Quantitative
Qualitative

36. #6(a). He drinks eight glasses of water each day.
(b). He drinks 2L of water each day.
Qualitative
Quantitative

37. Dilute vs. Concentrated
There is a small mass of dissolved solute for a certain quantity of solvent.
Concentrated
There is a large mass of dissolved solute for a certain quantity of solvent

38. Dilute vs. Concentrated- Explained Qualitatively

39. Dilute vs. Concentrated- Explained Quantitatively

40. Saturated vs. Unsaturated
Will form when no more solute will dissolve at a certain temperature
Unsaturated
More solute is able to dissolve at a certain temperature

43. Question to ponder…
Can a solution be considered to be concentrated be unsaturated? Explain

44. Question to ponder…
If there are two glasses on Kool Aid on the table, one is unsaturated the other is saturated. How would you be able to tell the difference between the two?

45. Question to ponder…
2. It is possible to “unsaturate a saturated solution”. Suggest ways you might be able to do this. (Hint: How could you make more sugar dissolve in a glass of water?)

46. Solutions and Solubility
Grade 7 Science
Solutions and Solubility

47. How Does Temperature Affect Solubility?
Complete Core Activity 8-2A page 268-9

48. Rate of Dissolving…
Factors that affect the rate of dissolving include:
Size of the solute
Temperature
Pressure

49. Size of Solute
The smaller the solute particles, the quicker they will dissolve
faster

50. Temperature
The higher the temperature, the more solute and the faster the solute will dissolve
faster

51. Pressure
Gases are more soluble in liquids under higher pressure (see page 267)
Opened bottle decreases pressure and “bubbles” come out of solution

52. Quantitative Description
Expressed as the amount of solute per unit volume. Examples: g/L g/mL ppm (parts per million) %

53. Converting g/mL to g/L
**Remember there are 1000mL in 1 L. 1g/mL = ? g/L 1 x 1000 = 1000 therefore 1000g/L

54. Practice Problems…
0.3g/mL = ? g/L
300g/L
8.9g/mL = ? g/L
8900g/L