Culver City H.S. · AP Chemistry Name ______

Period ___ Date ___/___/___

15 · Acid-Base Equilibria

TWO POINTS ON TITRATION CURVE

Titration curves are graphs of various points.

We want to determine two points on this curve, the initial pH and the pH at the equivalence point.

Points are always (x,y) where

x = volume of titrant; y = pH of the mixture

For our case, we plot (mL, pH)

1. Sample: 10.00 mL of 0.150 M HCl

Titrant: 0.200 M NaOH

a) pH of the original acid sample = ______

b) Volume of titrant needed to titrate the acid sample: ______mL

Work:

c) Two points you can plot:

beginning / equivalence point
( , ) / ( , )

d) Total volume of mixture at the equivalence point:
______mL = ______L

e) Moles of HCl at start: ______mol HCl

f) Moles of Cl- at start: ______mol Cl-

g) [Cl-] at equivalence point: ______M Cl-

Work:


2. Sample: 15.00 mL of 0.0200 M HCl

Titrant: 0.0175 M NaOH

a) pH of the original acid sample = ______

b) Volume of titrant needed to titrate the acid sample: ______mL

Work:

c) Two points you can plot:

beginning / equivalence point
( , ) / ( , )

d) Total volume of mixture at the equivalence point:
______mL = ______L

e) Moles of HCl at start: ______mol HCl

f) Moles of Cl- at start: ______mol Cl-

g) [Cl-] at equivalence point: ______M Cl-

Work:

3. Sample: 30.00 mL of 0.0250 M NaOH

Titrant: 0.0150 M HCl

a) pH of the original sample = ______

b) Volume of titrant needed to titrate the acid sample: ______mL

Work:

c) Two points you can plot:

beginning / equivalence point
( , ) / ( , )

d) Total volume of mixture at the equivalence point:
______mL = ______L

e) Moles of NaOH at start:
______mol NaOH

f) Moles of Na+ at start: ______mol Na+

g) [Na+] at equivalence point:
______M Na+

4. Sample: 25.00 mL of 0.100 M HC2H3O2

Ka HC2H3O2 = 1.8 x 10-5

Titrant: 0.0750 M NaOH

a) pH of the original acid sample = ______

Work:

b) Volume of titrant needed to titrate the acid sample: ______mL

Work:

c) It takes ______(more | less | the same) amount of base to titrate a weak acid as a strong acid.

d) Total volume of mixture at the equivalence point:
______mL = ______L

e) Moles of HC2H3O2 at start:
______mol HC2H3O2

Work:

f) Moles of C2H3O2- at start:

______mol C2H3O2-

g) [C2H3O2-] at equivalence point:
______M C2H3O2-

Work:

h) pH at the equivalence point: ______

Work:

i) Two points you can plot:

beginning / equivalence point
( , ) / ( , )


5. Sample: 10.00 mL of 0.125 M HF

Ka HF = 6.3 x 10-4

Titrant: 0.100 M NaOH

Two points you can plot:

beginning / equivalence point
( , ) / ( , )

6. Sample: 10.00 mL of 0.125 M NH3

Kb NH3 = 1.8 x 10-5

Titrant: 0.100 M HCl

Two points you can plot:

beginning / equivalence point
( , ) / ( , )