1. ACIDS & BaseS

2. What is the pH Scale? A scale which measures the degree of
acidity or alkalinity of an aqueous solution.
Ranges from 0 – 14.

3. Importance of pH:
pH of soil
pH of tank
pH of food

4. pH & Agriculture pH of soil
Excess acid in the soil can be neutralised by adding calcium hydroxide (slaked lime).
Farmers spread calcium hydroxide powder over their fields to neutralize acids.

5. pH of some common substances:1 2 3 4 5 6 7 8 9 10 11 12 13
pH = 14
pH = 0
Increasing
Acidity
Alkalinity
Neutral
HCL
Lemon Juice , Vinegar
Orange Juice
Acid Rain
Urine
Soft drink, Black Coffee
“Pure water”
Ammonia
Sea water
Baking Soda
Soap
Detergent
Sodium hydroxide

6. *pH Scale pH is a measure of how acidic or basic a solution is.
The pH scale ranges from 0 to 14.
Acidic solutions have pH values below 7
A solution with a pH of 0 is very acidic.
A solution with a pH of 7 is neutral.
Pure water has a pH of 7.
Basic solutions have pH values above 7.

7. Table M These indicators change colors in response to the [H+]
pH Indicators
Universal Indicator
Chemicals which change colors when they are put into acids or bases.
These indicators change colors in response to the [H+]
Table M

8. Common pH indicators:
Universal Indicator
Litmus paper
Phenolphthalein
Methyl orange
Bromthmymol blue
*Different colors are observed in solutions depending whether it is:
acidic or alkaline

9. pH Indicators

10. Some everyday things that contain acids

11. In fact, we even have acid in our stomach!!!

12. *Some Properties of Acids
Produce H+ (as H3O+) ions in water (the hydronium ion is a hydrogen ion attached to a water molecule)
Taste sour
Corrode metals
Are electrolytes
React with bases to form a salt and water
pH is less than 7
Turns blue litmus paper to red “Blue to Red A-CID”

13. What is the meaning of acids?
An acid is a substance that donates ___________ when it dissolves in water.
hydrogen ions,H+

14. *Acids produce hydrogen ions in water.
without water
water
*Acids produce hydrogen ions in water.
*Acids only show the properties of acids when they are dissolved in water.

15. *Acids ionize in water.
add water
It is the hydrogen ions which are responsible for acidic properties.

16. H2SO4 HNO3 HSO4- & H+ SO42- & H+ NO3- & H+ Common strong acids:
Formula:
Ions produced:
1.Sulfuric acid
H2SO4
HSO4- & H+
SO42- & H+
2.Nitric acid
HNO3
NO3- & H+

17. HClO4 HCl ClO4- & H+ Cl- & H+ Common strong acids: Formula:
Ions produced:
3. Perchloric acid
HClO4
ClO4- & H+
4. Hydrochloric acid
HCl
Cl- & H+

18. HBr HI Br- & H+ I- & H+ Common strong acids: Formula: Ions produced:
5.Hydrobromic acid
HBr
Br- & H+
6.Hydroiodic acid HI
I- & H+

19. Name ‘Em!
HI (aq)
HCl (aq)
H2SO4 (aq)
HNO3 (aq)
HClO4 (aq)
HBr (aq)

20. *What is the meaning of bases?
solution of hydroxide ions, OH-are produced when bases
dissolve in water.
NaOH  Na OH-
Ca(OH)2  Ca OH –

21. *Some Properties of Bases
Produce OH- ions in water (accepts H+ acceptor)
Taste bitter
Slippery texture
Are electrolytes (strength depends on concentration of hydroxide, OH-, ions)
React with acids to form a salt and water
pH is greater than 7
Turns red litmus paper to blue

22. NaOH KOH LiOH Na+ & OH- K+ & OH- Li+ & OH- Common strong bases:
Formula:
Ions produced:
1. Sodium hydroxide
NaOH
Na+ & OH-
2. Potassium hydroxide
KOH
K+ & OH-
3. Lithium hydroxide
LiOH
Li+ & OH-

23. RbOH CsOH Rb+ & OH- Cs+ & OH- Common strong bases: Formula:
Ions produced:
4. Rubidium hydroxide
RbOH
Rb+ & OH-
5. Cesium hydroxide
CsOH
Cs+ & OH-

24. Ca(OH)2 Ba(OH)2 Sr(OH)2 Ca2+ & 2OH- Ba2+ & 2OH- Sr2+ & 2OH-
Common strong bases:
Formula:
Ions produced:
6. Calcium hydroxide
Ca(OH)2
Ca2+ & 2OH-
7. Barium hydroxide
Ba(OH)2
Ba2+ & 2OH-
8. Strontium hydroxide
Sr(OH)2
Sr2+ & 2OH-

25. *A Brønsted-Lowry acid is a proton donor
*A Brønsted-Lowry base is a proton acceptor
conjugate acid
conjugate base
base
acid

26. ACID-BASE THEORIES
The Brønsted definition means NH3 is a BASE in water — and water is itself an ACID

27. conjugate acid-base pairs
Identify the acid, base, conjugate acid, conjugate base, and conjugate acid-base pairs:
HC2H3O H2O  C2H3O2– H3O+
acid
base
conjugate base
conjugate acid
conjugate acid-base pairs
OH – + HCO3–  CO32– H2O
acid
conjugate base
conjugate acid
base
conjugate acid-base pairs

28. Representative pH Values
pH Scale
The pH scale ranges from 0 to being the most acidic and 14 being the most basic.
So what does the pH tell us about [H+] of a solution?
If something has a pH of:
pH 1 = [H+] = 0.1 M
pH 2 = [H+] = 0.01 M
pH 3 = [H+] = 0.001M
pH 4 = [H+] = M
pH 5 = [H+] = M
pH 6 = [H+] = 1X 10-6M
pH 7 = [H+] = 1X 10-7M
pH 8 = [H+] = 1X 10-8M
pH 9 = [H+] = 1X 10-9M pH 10=[H+] = 1X 10-10M
pH 11=[H+] = 1X 10-11M
pH 12=[H+] = 1X 10-12M
pH 13=[H+] = 1X 10-13M pH 14=[H+] = 1X 10-14M
Representative pH Values
Substance pH
battery acid
0.5
gastric acid
lemon juice
2.4
cola
2.5
vinegar
2.9
orange juice
3.5
acid rain
tea
5.5
milk
6.5
pure water
7.0
saliva
blood
sea water
8.0
soap
ammonia
11.5
household bleach
12.5
lye (sodium hydroxide)
13.5

29. Given: H+ Calculating for pH Formula: pH = - log [H+]
*Given: H+ Calculating for pH Formula: pH = - log [H+] *Remember that the [ ] means Concentration (Molarity)
Example: If [H+] = 1 X pH = - log 1.0 X 10-10
pH = - (- 10)
pH = 10
Example: If [H+] = 1.8 X 10-5 pH = - log 1.8 X 10-5
pH = - (- 4.7)
pH = 4.7

30. How to Figure it out?
If you were given HCl with a concentration of 0.003M, what would be the pH?
pH = -log [H+]
pH = -log[0.003M]
pH = 2.5
pH will not have a unit!!!

31. How do pH and pOH relate? pH and pOH relate in the following way:
pH + pOH = 14
pOH is the measure of the [OH-], in a solution.
What would be the pOH of an solution with a pH of 5.8?
pOH = 14 – 5.8
pOH = 8.2

32. *Given [OH-] and calculating pH formula: pH=14-(-log [OH-])
What is the pH of the M NaOH solution?
[OH-]=
pH = 14- (-log )
pH = 14 - (3)
pH = 11

33. pH calculations: Solving for [H+]
If the pH of Coke is 3.12, [H+] = ???
Because pH = - log [H+] then
- pH = log [H+]
Take antilog (10x) of both sides and get
10-pH = [H+] or [H+] =antilog -pH
[H+] = = 7.6 x 10-4 M
*** to find antilog on your calculator, look for “Shift” or “2nd function” and then the log button

34. *Given-pH Calculating-H+ or H3O+ Formula: [H+] = antilog(-pH)
What is the [H+] of a solution with a pH of 12.05?
[H+] = antilog (-12.05)
[H+] = 10 (-12.05)
[H+] = 8.91 X M
*Antilog (2nd button of log): usually is 10x

35. Sample Problem 1
What is the pH and pOH of a solution with [H+] of 3.33 X 10-9 M?
1st solve for pH pH = -log [H+]
pH = - log[3.33 X 10-9 M]
pH = 8.48
2nd  solve for pOH
pOH = 14 – pH
pOH =
pOH = (acidic)

36. Sample Problem 2 What is the [H+] of a solution with a pOH of 4.14?
1st  determine pH pH = 14 – pOH
pH = 14 – 4.14
pH = (basic)
2nd determine [H+]
[H+] = antilog (-pH)
[H+] = antilog (-9.86)
[H+] = 1.38 X M

37. Sample Problem 3
What is the pH of a solution with a [OH-] = 2.35 X 10-9?
OH = 14-(-log [OH-])
pH = 14-(-log[2.35X10-9 M])
pH = (acidic)

38. Sample Problem 4 4.57g HCl 1 mol HCl = 0.125 mol HCl 36.46 g HCl
What is the pH of a solution that was made from 4.57g of HCl dissolved in 750 mL of water?
1st  determine moles of HCl
4.57g HCl
1 mol HCl =
0.125 mol HCl
36.46 g HCl

39. Sample 4 ….
2nd determine concentration of [H+], since this is an acid the [H+] would be the same as the concentration(molarity “M”) of the whole molecule of HCl. We will get [H+] & [Cl-], both with the total of moles each.
So concentration “M” will be moles / volume (L)
[H+] = moles/ L
[H+] = 0.333M

40. Problem 4… Next determine pH pH = -log [H+] pH = -log [0.333M]
pH = (very acidic)

41. Try These! Find the pH of these:
1) A 0.15 M solution of Hydrochloric acid
2) A 3.00 X 10-7 M solution of Nitric acid

42. Neutralization reaction
Bases reacts with an acid to produce a salt and water
ACID + BASE --> SALT + WATER
HCl + NaOH > NaCl + H2O

43. *Neutralization reactions
- Products are always water and salt
Perform titrations to determine an unknown volume or concentration of an acid/base
ENDPOINT = when indicator changes color
Moles of H+ = Moles of OH-
MAVA = MBVB
MA= molarity of acid
VA= volume of acid
MB= molarity of base
VB= volume of base

44. *Titration:
A laboratory method for determining the concentration of an unknown acid or base using a neutralization reaction.
A standard solution,(a solution of known concentration), is used.

45. *Equivalence Point
The point at which there are stoichiometrically equivalent amounts of acid and base.
[H+] = [OH-]

46. Methods of Solving Titration Problems:
a) using stoichiometry
b) using the titration formula MaVa=bMbVb.

47. Setup for titrating an acid with a base

48. Buret
Stopcock
Ring Stand

49. Titration
Acid with Phenolpthalein
End-Point

50. Titration problems MAVA = MBVB (MA)(34.57ml) = (0.1025M)(25.19ml)
Calculate the molarity of an acetic acid solution if mL of this solution are needed to neutralize cL of M sodium hydroxide
MAVA = MBVB
MA= molarity of acid
VA= volume of acid
MB= molarity of base
VB= volume of base
(MA)(34.57ml) = (0.1025M)(25.19ml)
MA= M

52. Ex. 1
What is the concentration of HCl if 30.0 mL of 0.10 M NaOH neutralizes 50.0mL HCl?
NaOH + HCl  H2O NaCl
Hint: Use MaVa=bMbVb
Ma=
How many moles of HCl were used?
Hint: #moles= MaVa , but convert the volume to L( 50mL=0.05L).

53. Ex. 2
A 20.0 mL solution of Sr(OH)2 is neutralized after 25.0 mL of standard 0.05 M HCl is added. What is the concentration of Sr(OH)2?
2 HCl + Sr(OH)2  2 H2O + SrCl2

54. Ex. 3
How many mL of 0.20 M H3PO4 are needed to neutralize 55.0 mL of a 0.10 M solution of NaOH?

55. Ex. 4
What volume of 0.20M Ca(OH)2 will neutralize 45.0 mL of a 1M solution of HClO3?

56. Practice!
Give two ways that acids are different from bases that does not include their pH.

57. Practice! Titration problems MAVA = MBVB (0.5M)(20.0ml) = MB(65.0ml)
If 20.0ml of a 0.50M HCl solution is needed to neutralize 65.0ml of a NaOH solution. What was the concentration of the base?
MAVA = MBVB
MA= molarity of acid
VA= volume of acid
MB= molarity of base
VB= volume of base
(0.5M)(20.0ml) = MB(65.0ml)
MB= 0.154M

58. Practice! Titration problems
43.0ml of HCl was titrated with 32.0 ml of M NaOH. What is the molarity of the hydrochloric acid solution?
MAVA = MBVB
MA= molarity of acid
VA= volume of acid
MB= molarity of base
VB= volume of base
MA(43.0ml)=(0.100M)(32.0ml)
MA= M

59. Practice! What is the [H+] of an acid with a pH of 5.56?
Determine the pH of a M HCl?
Determine pOH of a solution with a pH of 8.7?
What is the pH of a base with an [OH-] of X10-5 M?
Answers: [H+] is 2.75X
pH = -log[H+] = 2.3
pOH is 5.3 ( = 5.3)
pH is 9.5 (because pOH= 4.5)