1. TOPIC: pH
Do Now: Identify as acid, base, salt, or covalent Electrolyte or Not
1. NaCl
6. CaI2
2. C2H5OH
7. HF
3. H2SO4
8. Mg(OH)2
4. NaOH
9. NH3
5. C12H22O11
10.CH3COOH
1. SALT - ELECTROLYTE
6. SALT - ELECTROLYTE
2. COVALENT -NO
7. ACID- WEAK ELECTROLYTE
8. BASE- ELECTROLYTE
3. ACID- ELECTROLYTE
9. BASE- WEAK ELECTROLYTE
4. BASE- ELECTROLYTE
5. COVALENT -NO
10. ACID- WEAK ELECTROLYTE

2. pH scale P= power of H = Hydorgen Ranges from measures H+ concentration [H+] the more H+, the more acidic the solution

3. Acid, Base, or Neutral Neutral solution: pH = 7
Acidic solution: pH LESS THEN 7
Basic solution: pH GREATER THEN 7

4. Every Acidic/Basic solution contains H+ and OH-
For acids
For bases
when [H+] = [OH-] the substance is neutral
so we can actually measure pH and pOH
pH + pOH =14
H+1 > OH-1
OH-1 > H+1

5. Logarithmic scale (based on powers of 10)
each decrease of one unit of pH represents a 10x increase in H+ concentration
Ex: pH 4 is ten times more acidic then pH 5
Ex: pH 10 is ten times more basic then pH 9
Try to remember: The lower the pH, the higher the concentration of H+ ions

6. Lets Practice
When the pH of an aqueous solution is changed from 1 to 2, the Hydrogen ion concentration
Decreases by a factor of 2
Decreases by a factor of 10
Increases by a factor of 2
Increases by a factor of 10
A solution with a pH of 2.0 has a hydronium ion concentration ten times greater than a solution with a pH of
1.0 b) c) 3.0 d) 20
Which change in pH represents a hundredfold increase in the concentration of hydronium ions in a solution
pH 1 to pH 2
pH 1 to pH 3
pH 2 to pH 1
pH 3 to pH 1

7. We are going to learn an easier way!
Calculating pH
pH=-log [H+]
[H+] = concentration
Ex. 0.01M HCl has a pH of?
This means you have .01 moles of H+
and .01 moles of Cl- per every 1 L
pH = -log(0.01)
pH=2
We are going to learn an easier way!

8. Because it’s based on powers of 10 there is a trick 10-x where x = pH
If molarity of acid is .001M =10-3 pH = 3
If molarity of acid is M = 10-5 pH = 5

9. pH of a base Now you are looking at OH- ions instead of H+
ONLY CAN CALC pOH
pOH=-log [OH-] or our trick 10-x where x = pOH
pH + pOH = 14
So 14 – pOH = pH
Ex. 0.01M NaOH has a pH of?
This means you have .01 moles of OH-
and .01 moles of Na+ per every 1 L
pOH=2
pH = 14-2 = 12

10. Because it’s based on powers of 10 there is a trick
If molarity of base is .001M = 10-3 pOH = 3
pH 14-3 = 11
If molarity of base is M = 10-5 pOH = 5
pH 14-5 = 9

11. If pH = 4 [H+1] = ? pOH = ? [OH-1] = ? 1 x 10-4 M 1x10-10 M = [OH-1]
pH + pOH = 14
4 + X = 14
X =10
1x10-10 M = [OH-1]

12. If the [OH-1] = 1 X 10-3 M pOH = ? pH = ? [H+1] = ? pOH = 3
pH + pOH = 14
X + 3 = 14
X = 11
1x10-11 M

13. The pH = ? The pOH = ? The [OH-] = ? =5 pH + pOH =14 5+x =14 X=9
If the [H+1] = 1 x 10-5 M
The pH = ?
The pOH = ?
The [OH-] = ? =5
pH + pOH =14
5+x =14
X=9
1x10-9M

14. Calc pH for 10-2 = 2 so pH = 2 10-2 = 2 so pOH = 2 14-2 – 12 pH=12
.01M HCl
.01M NaOH
10-2 = 2 so pH = 2
10-2 = 2 so pOH = 2
14-2 – 12
pH=12