1. A Matter of Concentration
Chapter 5
A Matter of Concentration

2. Classification of Matter ( fig. 5.1 p.5.5)
Pure substances
elements
compounds
Mixtures
Homogenous
solutions
Heterogeneous
Suspensions
Mechanically separable substances

3. Matter Everything that has volume and mass
Horse head nebula photo from nasa

4. Pure substances
A pile of only one substance, with absolutely nothing else in it.
Mercury, nickel sulfate, sugar

5. Elements Chemical elements
Diamond ( carbon), Graphite (carbon), bismuth

6. Compounds
More than one element in molecule, but all; the same molecule
Silver oxide, silver iodide, silver nitrate, silver sulphate, silver cyanide

7. Mixtures Combinations of substances
Chromium (II) Chloride, misc solutions, salad, orange juice, salad dressing

8. Homogenous The entire mixture looks the same Also called solutions
Air is a solution
Salt into water

9. Heterogeneous Mixtures
Mixture where you can see different parts

10. Heterogeneous - Suspensions
Largish particles floating in liquid
Orange juice, tomato juice, salad dressing, chocolate milk

11. Heterogeneous – mechanically separable substances
Things that can be separated by mechanical means
Mixed sand in an oregeon creek bed, chocolate chip cookies, salad, pizza

12. Solutions Contains solvent, which does the dissolving
Solute, which is dissolved
Calcium sulphate, and paint solvents

14. Concentration Concentration (c) = Unit : g/L e.g.
c = m/V = 1g/1L = 1g/L
10g/1L = 10g/L
20g/0.5L = 40g/L
20g/2L = 10g/L
Dilutions of grenadine

15. Watch Your units! Mass in grams Volume in liters
1000 g = 1 Kg
Volume in liters
1000 ml = 1 L
Convert if you have to

16. Concentration in ppm
You must convert  mg = 1g x 1000

17. Try these
Calculate the concentration in ppm for the following? 200mg of NaCl in 1L water 50 mg of NaCl in 50 mL water 100 g of NaCl in 200L water 0.05 g of NaCl in 250 mL

18. Percent mass/mass (%m/m)

19. Suppose we prepared a solution by mixing 8
Suppose we prepared a solution by mixing 8.00 g of KCl (solute) with g of water (solvent). What is the concentration of the solution in %m/m?

20. A solution is prepared with 15. 0 g of Na2CO3 and 235 g of H2O
A solution is prepared with 15.0 g of Na2CO3 and 235 g of H2O. What is the mass percent (m/m) of Na2CO3 in the solution?

21. A solution of NaCl is prepared using 20 g of salt and 300 grams of water what is the concentration in %m/m

22. Percent mass/ volume (%m/v)

23. Water is added to 5. 0 g of KI to make 250 mL of KI solution
Water is added to 5.0 g of KI to make 250 mL of KI solution. What is the mass/volume percent of the solution?

24. Water is added to 6. 5 g of sugar to make a 350mL solution
Water is added to 6.5 g of sugar to make a 350mL solution. What is the %m/v concentration of the sugar?

25. Percent volume/volume (% v/v)
Volume can be in any unit as long as it is the same for the solute and solvent

26. A bottle contains 59 mL of lemon extract solution
A bottle contains 59 mL of lemon extract solution. If the solution contains 25 mL of alcohol, what is the volume percent (v/v) of the alcohol in the extract solution?

27. A bottle of vinegar contains 25 mL of vinegar in 1 L of water, what is the concentration in percent volume/volume?

28. Chemical reactions Occur in number of atoms
Atoms are really small, and there are trillions of them
Trying to work by number of atoms, would be like buying rice by the number of grains.
So…..

29. The Mole Is awesome chemicals react in multiples of moles
1 mole of an element weighs it’s mass number in grams
Avogradro, a mole

31. Molar mass
How much 1 mole of a substance weighs

32. How to calculate the number of moles
Work out the molar mass
Divide amount from question by molar mass
e.g.
96g of MgCl2

33. P.225 #

34. Molarity
Concentration using moles per liter
Unit: mol/L or M

35. Eg. 6 moles NaCl in 300 ml
35 g NaCl in 750 ml

36. How many grams of NaCl are needed to make 500 ml of a 1.6 M solution?

37. P.230#

38. Number of Molecules
# of molecules= # moles x Avagadros # (6.023 X 1023)
How many molecules of O2 do you have if you have 1.5 moles?
How many moles of Cl2 do you have if you have 2.25 x moles?

39. Conversions % m/V = grams of solute / 100 mL of solution
Example Find the molarilty of 0.5 % m/v NaCl
1. 0.5/100 = x g/ 100ml = 0.5 g
2. Convert grams to mole using triangle.
n = m/mm = 0.5 /55.84g/mol = 8.9 x 10 -3moles
3. Molarity = n/v where the v is 100mL
C = 8.9 x /.1 L =0.089 M

40. Your turn Convert the following into molarity
5 % m/v acetic acid (CH3COOH)
Wine has 12% alcohol /volume (C2H6O)
Rubbing alcohol has 70% isopropyl alcohol / volume (C3H8O)

41. ppm to Molarity ppm = mg of solute/L solution Convert mg to g
Convert g to moles
C=n/v

42. P

43. You are to administer a glucose (C6H12O6 ) solution to a patient which of the following solutions is the strongest?
Solution 1
Solution 2
Solution 3
4.5 % m/v
0.3 mol/L
38 ppm

44. Solubility
The maximum amount of solute(stuff) that you can dissolve in a given volume of solvent(your liquid).
Unit in g/100mL

45. Solubility
The maximum quantity of the substance that can be dissolved in a given volume of solvent . (g/100mL)
Example: What is the maximum quantity of salt that can be dissolved in 100mL of water.?
Once the maximum is reached, the solution is known as saturated, and salt will precipitate( fall to the bottom)

46. Solubility depends on Temperature Pressure What solvent you use
What solute you use

47. Dilution C2 = final concentration C1 = initial concentration
V2 = final volume
C1 = initial concentration
V1 = initial volume

48. Ex. Susie is preparing a 2 molar sugar solution. She needs 4L of it
Ex. Susie is preparing a 2 molar sugar solution. She needs 4L of it. If she has 250 ml of 10 molar syrup can she make up her solution?

49. Ex. Abdullah has to prepare 1 L of a 0. 1 molar solution of NaCl
Ex. Abdullah has to prepare 1 L of a 0.1 molar solution of NaCl. He has 4L of 10 M stock solution. how much stock solution must he use?

50. pH Therefore Is the concentration of H+ ions in a solution
pH = -log [H+]
Therefore
low pH = highly acidic
High pH = less acidic
pH 7 is neutral

52. Concentrations of H+ are expressed as 1 X 10-4
The small number (flip the sign) is your pH
E.g. the above example has a pH of 4
1 X 10-5
1X10-8

53. Acid-Base Indicators
There are chemicals that change colour in different pH’s
The pH at which they change colour is called the turning point

54. indicator
Turning point
Colour change A
Yellow – blue B
Blue – violet C
Violet – green D
Green - orange
Indicator
result
interpretation A
Blue B
Yellow C
Green D
orange

55. indicator
Turning point
Colour change A
Yellow – blue B
Blue – yellow C
Violet – green D
Green - orange
Indicator
result
interpretation A
Blue B
blue C
violet D
green

56. indicator
Turning point
Colour change A
Yellow – blue B
Blue – violet C
Violet – green D
Green - orange
Indicator
result
interpretation A
Blue B
yellow C
violet D
green

57. Litmus Paper
Blue = Base
Red = Acid
One red, one blue = Neutral

58. Which is a non-electrolyte? Which is a base? Which is a weak acid?
Which is a strong acid?
Which is a non-electrolyte?
Which is a base?
Which is a weak acid?
Red litmus paper
Blue litmus paper
conductivity A
red + B
blue
++++ C
Red
None D

59. Which is a strong acid? Which is a salt? Which is a base?
Which is a weak base?
Red litmus paper
Blue litmus paper
conductivity A
blue + B
++++ C
Red D
red