1. Grade 7 Science Chapter 8

2. Solutions… a review zA solution is a homogeneous mixture yie. they appear as ONE substance Examples: ytap water yVinegar ygold jewelry

3. Making solutions: solutes and solvents zWhen you mix two substances and they form a solution, you say that one substance dissolves in the other substance.

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

5. Dissolving... zTo mix completely: ythe solute dissolves into the solvent.

6. Different states of solutes and solvents p. 255 zSolvents can be either: ySolid, Liquid, Gas z Solutes can be either: ySolid, Liquid, Gas SolutionSoluteSolventState of solute State of solvent AirOxygen, carbon dioxide and other gases NitrogenGas Soda waterCarbon dioxideWaterGasLiquid VinegarAcetic acidWaterLiquid Filtered ocean water Sodium chloride (salt) and other minerals WaterSolidLiquid BrassZincCopperSolid antifreezeAlcoholwaterLiquid

7. Can you guess what the example is? Hydrogen in Palladium

8. SoluteSolventState Vinegar Air Soda Filtered sea water Brass Sugar water

9. Vinegar 5% acetic acid 95% water Liquid

10. Air -78%: Nitrogen - 22%: oxygen, carbon dioxide, other gases Gas

11. Soda - carbon dioxide - water Gas Liquid

12. Filtered Sea Water - Water - Salt and other minerals Solid Liquid

13. 100 % Brass - 35g zinc - 65% copper Solid **Alloy: Solutions made from two or more metals.

14. Sugar water - 1 teaspoon of sugar - 1 cup of water Solid Liquid

15. In class activity z8-1A: Name that solute and solvent yP.255

16. SOLUBLE AND INSOLUBLE p.256

17. Soluble zIf the particles of the solute are more attracted to the particles of the solvent. yDissolving occurs. yThe solute is said to be soluble in that solvent. (ie. Solution) https://www.youtube.com/watch? v=khgOTDvG-4A

18. Insoluble zIf the particles of the solute are more attracted to their own particles than the solvent particles. yDissolving does NOT occur. yThe solute is said to be insoluble in that solvent. (ie. Mechanical)

19. Soluble or Insoluble? soluble insoluble

20. Insoluble in some solvents, soluble in others p.257

21. Why some substances dissolve p.258 1.Solute becomes attracted to the solvent. ySolute particles are attracted to solvent particles - so they mix. xExample: sugar particles are attracted to the water particles, mixing with the water particles. 2.Movement yMixing causes movement. When 2 substances are mixed, the weak attractions are broken by the motion of the particles. xExample: oil is mixed with gasoline. Both have very weak attractions that are broken by the motion.

23. Why some substances do not dissolve zSolute is NOT attracted to the solvent.  For fat particles to dissolve in water, the milk fat particles would have to be more attracted to the water particles.  Fat particles are not more attracted to the water particles.  Fat particles stay together and form insoluble globules in the liquid Milk

24. In class activity zReading check p.257 & 258 zCheck your understanding p. 261

25. CONCENTRATION AND SOLUBILITY 8.2 Page 262

26. Concentration and solubility zCompare the two cups of tea… z Concentrated solution yDarker tea yLarge mass of dissolved solute for a certain quantity of solvent. z Dilute solution yLighter tea ySmall mass of dissolved solute for a certain quantity of solvent

28. Concentration is… zThe quantity of solute that is dissolved in a certain quantity of the solvent. zCan be described qualitatively or quantitatively.

29. Qualitative Using words such as like “dilute” or “concentrated” Quantitative Using numbers. This is especially important when safety is an issue!

30. Student Practice… (page 471) Qualitative or Quantitative? z#1(a).Food coloring made the water blue. zQualitative z (b).Adding 3 mL of food coloring turned 250 mL of water blue. zQuantitative

31. z#2(a).The water became warmer. zQualitative z (b).The water’s temperature increased by 5 degree Celsius. zQuantitative

32. z#3(a).We needed just over a dozen floor tiles for our model room. zQualitative z (b).We needed 14 floor tiles for our model room. zQuantitative

33. z#4(a).The liquid boiled in 5 min. zQuantitative z (b).The liquid took only a few minutes to boil. zQualitative

34. z#5(a).The mass of this solid is 5g more than that one. zQuantitative z (b).This solid is heavier than that one. zQualitative

35. z6(a).He drinks eight glasses of water each day. zQualitative z (b).He drinks 2L of water each day. zQuantitative

36. A limit to concentration p.264 zMake a salt solution: yAdd a spoonful… dissolved! yAdd a second spoonful… dissolved! yAdd a third, fourth and more… It becomes more concentrated! zEventually you reach a point where salt will NOT dissolve any more. Notice the lump of undissolved solid that is left on the spoon

37. Saturated vs. Unsaturated Saturated zWill form when no more solute will dissolve at a certain temperature Unsaturated z More solute is able to dissolve at a certain temperature

38. Concentration is… zExpressed as the amount of solute per unit volume. zExamples:-g/L or g/mL -ppm (parts per million) - percentage be mass

39. Which is dilute and which is more concentrated for each example? zExample 1: yOrange juice from concentrate: ___________ yWeak Kool-Aid: ____________________ zExample 2: yA solution with a concentration: 20g/100mL _______ yA solution with a concentration: 25g/25mL_________ zExample 3: yA solution with a concentration: 20/80mL__________ yA solution with a concentration: 20/100mL ________

40. Time to think… zConcentrated solutions can be: 1.Adding more solute and keeping the amount of solvent the same. 2.Keeping the amount of solute the same and reducing the amount of solvent. yExample x boiling off the water while making jam za solution could be considered “concentrated” and still be unsaturated.

41. In class activity

42. Rate of dissolving p.265 zThe rate of dissolving refers to how quickly a solute dissolves in a solvent. zFactors that affect the rate of dissolving include: 1.Stirring 2.Temperature 3.Size of solute 4.Pressure

43. 1. Stirring zA solute will dissolve more quickly if you stir it. zExample: fruit drink with drink crystals. yStir the mixture to increase the rate of dissolving.

44. Stirring: PTM p.265 A: Before mixture is stirred. zMovement depends on the natural movement of the nearby water particles. zThe solution close to the crystal is more concentrated and the solution farther from the crystal is more dilute. B: While stirring mixture zThe solute and solvent interact more quickly. zThe concentrated solution is pushed away from the crystal at the same time it pushes dilute solution closer to the crystal.

45. 2. Temperature - SOLID zAs temperature increases: y The faster the solute will dissolve.

46. Temperature - GAS zAs temperature increases: y The solubility of a gas generally decreases. yIt will taste: “flat” - warm pop if left open for a period of time http://www.youtube.com/watch?v=K3j9 HAsoV5Q

47. 3. Size of solute zSmaller pieces of solute will dissolve more quickly than larger pieces. yDissolving a solid in a liquid takes place at the surface of the solid. yBreaking a large solid into smaller pieces, expose more surfaces - creating a larger surface for the solvent to interact with.

48. 3. Pressure page 267 zGases are more soluble in liquids under higher pressure.

49. Pressure: Open a bottle or can of pop! zAs pressure increases, the solubility of a gas generally increases. yHigher pressure forces extra gas particles into the spaces between the water particles. zAs pressure decreases, the solubility of a gas generally decreases. yOpen the can and the pressure inside lowers quickly. Gas solute comes out of the solution. IE: bubbles

50. CORE LABORATORY ACTIVITY: HOW DOES TEMPERATURE AFFECT SOLUBILITY?

51. In class activity