1. CH 15 Acid-Base Titration and pH 15
CH 15 Acid-Base Titration and pH 15.1 Aqueous Solutions and the Concept of pH
Recall: acids and bases make hydronium (H3O+) and hydroxide (OH-) ions in aq solns
Pure water is an extremely weak electrolyte and undergoes self-ionization

2. Conductivity measurements
H3O+ and OH- in pure water are each only 1.0x10 -7 mol/L
Kw=[H3O+ ] [OH- ]
Neutral
Concentration H3O+ = conc. OH-
Acidic
Conc. H3O+ > conc. OH-
Basic
Conc. H3O+ < conc. OH-

3. Mole ratios to tell H3O+ or OH-
Calculating H3O+ & OH-
write ionic equation
Mole ratios to tell H3O+ or OH-
[H3O+][OH- ]= 1.0x M2
Don’t forget sig figs!
*Link for video*

4. pH = -log [H3O+] pOH = -log [OH-] pH + pOH = 14.0
Increasing H3O+ means decreasing pH
pH is logarithmic function, each unit represents a 10-fold difference; pH 3 is 10x greater than pH 4
pOH = -log [OH-]
pH + pOH = 14.0

5. Calculating pH using [H3O+ ]
write ionic equation
Mole ratios to tell H3O+
pH = -log [H3O+]
*Link for video*

6. Calculating pH using [OH-]
[H3O+][OH−] = 1.0 × 10−14 M2
Solve for [H3O+]
pH = -log [H3O+]
Problem C

7. Calculating from pH to [H3O+]
Calculating pH using [OH-]
pH = -log [H3O+]
-pH = log [H3O+]
antilog(-pH)= [H3O+] or
1.0 x 10 –pHw = [H3O+]
Problem D

8. 15.2 Determining pH and Titrations
Acid-base indicators
are compounds which change color with changes in pH
are organic
Act as very weak Bronstead-Lowry acids or bases
Change color when accept proton from acid or donate proton to base

9. pH paper is different from litmus paper!
pH paper has multiple indicators (thus color spectrum it can display)
pH meter gives reading/measurement from voltage changes of [H3O+]

10. Titration Used to determine exact concentrations
Control addition of solution with known concentration
Measure amount of solution of unknown concentration

11. Recall neutralization
Titration is way of determining chemically equivalent amounts of acids and bases
End point: when the indicator changes color at end of titration

12. Standard solution: aka known, has known concentration
Primary standard: purified solid solution used to check concentration of known solutions in titration
Equivalence point occurs ½ way between 2 points where line curves

14. Solving M of unknowns
Balanced equation
Determine moles of acid/base of known
Determine moles of solute of unknown used in titration
Calculate M of unknown soln