1. pH

2. pH Scale Typical values range from 0 to 14 pH = 7 – neutral
pH > 7 – basic
pH < 7 – acidic
A solution has a pH of Is it an acid or a base?
A solution has a pH of Is it an acid or a base?

3. pH in Common Solutions

4. Which of the following below is a strong acid?
H3PO4
HC2H3O2 HF
HNO3
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5. Which of the following is a weak base?
NH3
KOH
Ca(OH)2
NaOH
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6. What color do acids turn litmus paper?
green
red
purple
blue
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7. The base plus the accepted proton is the
acid
base
conjugate acid
conjugate base
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8. A substance that increases the hydronium ion concentration is a
Bronsted-Lowry Acid
Bronsted-Lowry Base
Arrhenius Acid
Arrhenius Base
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9. A substance that accepts a proton is a
Bronsted-Lowry Acid
Bronsted-Lowry Base
Arrhenius Acid
Arrhenius Base
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10. What is the acid in the reaction below: HClO4 + H2O  H3O+ + ClO4-
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11. What is the conjugate acid in the equation below: CH3COOH + H2O  H3O+ + CH3COO-
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12. Measurement of Acidity
pH represents the power of the Hydrogen
Negative logarithm of the H+ concentration (molarity)
pH = -log [H+]
What is the pH of a solution that has a hydrogen ion concentration of 1x10-7M?
pH = -log (1X10-7)
pH = 7

13. What is the pH of 1 x 10-3M of HCl?

14. What is the pH of 2.4x10-6M H3PO4?
What is the pH of 1.7x10-3M H2SO4?
What is the pH of 7.2x10-4M HI?

15. pOH pH + pOH = 14 If the pH is 5, what is the pOH?

16. What if you are asked to find the pH of a base?
What is the pH of 1x10-4 NaOH?
1. calculate the pOH by using
pOH = -log[OH-]
pOH = -log(1x10-4)
pOH = 4
2. pH + pOH = 14
pH + 4 = 14
pH = 10

17. What is the pH of 3.9 x 10-4M of NaOH? What is the pH of
1.4x10-2M of Mg(OH)2?
3. What is the pOH of
6.7x10-3M of LiOH?

18. What is the pOH of a 5.3x10-4M solution of HCl?
1. pH = -log[H+]
pH = -log(5.3x10-4)
pH = 3.28
2. pH + pOH = 14
pOH = 10.72

19. What is the pH of a 1X10-8M solution of HCl?5 6 8 1
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20. What is the pH of a 1X10-4M solution of NaOH?6 11
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21. What is the pH of an HCl solution that has a concentration of 2
What is the pH of an HCl solution that has a concentration of 2.9 x 10-8M? 8
6.46 6
7.54
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22. What is the pOH of a solution that has a hydronium concentration of 2
What is the pOH of a solution that has a hydronium concentration of 2.6 x 10-4M? 4
3.6
10.4
9.6
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23. If a solution has a hydrogen ion concentration of 0
If a solution has a hydrogen ion concentration of 0.003, what is the pH?
11.48
2.52
5.66
9.39
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24. What is the pH if the hydroxide ion concentration is 3.95 x 10-8M?
7.4
3.0
6.6
5.8
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25. A 1. 8L solution containing 0. 009mol of HCl is prepared
A 1.8L solution containing 0.009mol of HCl is prepared. What is the pH of this solution?
1. molarity = moles of solute
liters of solution
molarity = 0.009mol
1.8L
molarity = 0.005M
2. pH = -log[H+]
pH = -log(0.005)
pH = 2.3

26. 15000ml of a solution containing 0. 0003mol of HNO3 is prepared
15000ml of a solution containing mol of HNO3 is prepared. What is the pH of this solution?

27. [H3O] = antilog (-3) [H3O] = 0.001M or 1x10-3M
Calculating the concentration from the pH
[H3O+] = antilog (-pH)
What is the hydronium concentration of an acid solution having a pH of 3?
[H3O] = antilog (-3)
[H3O] = 0.001M or 1x10-3M

28. [H3O+] = antilog (-pH)
[OH-] = antilog (-pOH)
pH + pOH = 14
What is the hydroxide concentration of a solution that has a pH of 6.3?
1. pH + pOH = 14
6.3 + pOH = 14
pOH = 7.7
2. [OH-] = antilog (-pOH)
[OH-] = antilog (-7.7)
[OH] = 2.0x10-8M

29. What is the hydroxide ion concentration of a solution with a pH of 8.5? What is the hydrogen ion concentration of a solution with a pOH of 4.6?

30. [H3O+][OH-] = 1 x 10-14
If the hydronium ion concentration is 3.4 x 10-5M, what is the hydroxide ion concentration?
(3.4x10-5)[OH-] = 1x10-14
[OH-] = 1x10-14
3.4 x10-5
[OH-] = 2.9x10-10M

31. If the hydroxide ion concentration is
7.9 x 10-3M, what is the hydronium
ion concentration?

32. What is the concentration of KOH if the pH is 8?
1x108 M
1x10-6 M
1x10-10 M
1x10-4 M
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33. What is the hydronium concentration if the hydroxide concentration is 6.1 x 10-11M?
10.21
1.64 x 10-4M
3.79
6.1 x 10-3M
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34. If a solution has a pH of 8.5, what would this solution be classified as?
Weak acid
Weak base
Strong acid
Strong base
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35. What is the concentration of HCl if the solution has a pH of 2?
1x10-12 M
1x10-8 M
1x10-2 M
1x10-3 M
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36. What is the hydronium ion concentration for pure water?7 14
1 x 10-14M
1 x 10-7M
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37. What are the hydronium and hydroxide ion concentrations in a solution that is 1.0x10-4 M H2SO4?

38. What is the hydronium concentration of an acid solution having a pH of 5.3?

39. What is the hydronium ion concentration of a solution of H2SO4 with a pH of 2.1?
2.1 x 10-4M
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40. What is the hydroxide ion concentration of a solution that has a pH of 5.2?
8.8M
1.58 x 10-9M
6.31 x 10-6M
4.22 x 10-5M
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41. Indicators Compounds whose colors are sensitive to pH
Methyl orange – changes colors with a pH between 3.1 and 4.4
Phenolphthalein – changes colors with a pH between 8.0 and 10.0

42. Nature’s Indicator
Many flowers and plants contain acid/base indicators which change color in response to a change in pH
Chemical structure changes when pH changes

43. If a solution ionizes almost completely to form OH- ions, what is the substance?

44. What is a conjugate acid/base pair in the following equation
What is a conjugate acid/base pair in the following equation? HCN + H2O  H3O + CN-

45. When the hydroxide ion concentration is greater than the hydronium ion concentration, is the solution an acid or a base?

46. What is the pH of a 3.2 x 10-6M?

47. What is the pH of a 1.0 x 10-3M solution of NaOH?