Activity

1
Chapter 8

• Activity

2
HomeworkChapter 8 - Activity

• 8.2, 8.3, 8.6, 8.9, 8.10, 8.12

3
Question 8.2

• Q Which statements are true?
• In the ionic strength, m, range of 0-0.1 M,
  activity coefficients decrease with
• a) increasing ionic strength
• b) increasing ionic charge
• c) decreasing hydrated radius

All are true!!
4
Question 8.3

• Calculate the ionic strength of
• 0.0087 M KOH
• 0.0002 M La(IO3)3 (assuming complete dissociation
  at low concentration)

Ionic strength (m) ½ (c1z12 c2z22 )
½ 0.0087M(1)2 0.0087M(-1)2 0.0087
M
Remember for 1/-1 systems Ionic strength, m
Molarity, M
5
Question 8.3 (contd)

• Calculate the ionic strength of
• 0.0087 M KOH
• 0.0002 M La(IO3)3 (assuming complete dissociation
  at low concentration)

Ionic strength (m) ½ (c1z12 c2z22 )
½ 0.0002M(3)2 0.006M(-1)2 0.0012
M
6
Question 8.6

• Calculate the activity coefficient of Zn2 when m
  0.083 M by using (a) Equation 8-6 and (b)
  linear interpolation with Table 8-1.

a)
-0.375
g0.422
7
Question 8.6 (contd)

• Calculate the activity coefficient of Zn2 when m
  0.083 M by using (a) Equation 8-6 and (b)
  linear interpolation with Table 8-1.

0.432
8
Question 8-9

• Calculate the concentration of Hg22 in saturated
  solutions of Hg2Br2 in 0.00100 M KNO3.

Hg2Br2(s) D Hg22 2Br- Ksp5.6x10-23
some - - -x x 2x some-x x 2x
I C E
9
8-10.

• Find the concentration of Ba2 in a 0.100 M
  (CH3)4NIO3 solution saturated with Ba(IO3)2 (s).
• Ba(IO3)2 ? Ba2 2IO3 Ksp 7.11 x 10-11

some - 0.100 -x x 2x some-x x 2x
I C E
10
(No Transcript)
11
(No Transcript)
12
8-10.

• Find the concentration of Ba2 in a 0.100 M
  (CH3)4NIO3 solution saturated with Ba(IO3)2 (s).
• Ba(IO3)2 ? Ba2 2IO3 Ksp 1.5 x 10-9

some - 0.1 -x x 2x some-x x 0.12x
I C E
13
8-10.

• Find the concentration of Ba2 in a 0.100 M
  (CH3)4NIO3 solution saturated with Ba(IO3)2 (s).
• Ba(IO3)2 ? Ba2 2IO3 Ksp 1.5 x 10-9

some - 0.1 -x x 2x some-x x 0.12x
I C E
X 6.57 x 10-7
14
Question 8-12

• Using activities correctly, calculate the pH of a
  solution containing 0.010 M NaOH plus 0.0120 M
  LiNO3. What is the pH if you neglected
  activities?

(m) ½ (c1z12 c2z22 ) ½
0.010M(1)2 0.010M(-1)2 0.0120M(1)2
0.0120M(-1)2 0.0220 M gOH 0.873 pH AH
HgH
15
Question 8-12 (contd)

• Using activities correctly, calculate the pH of a
  solution containing 0.010 M NaOH plus 0.0120 M
  LiNO3. What is the pH if you neglected
  activities?

pH 11.94
16
Question 8-12 (contd)

• Using activities correctly, calculate the pH of a
  solution containing 0.010 M NaOH plus 0.0120 M
  LiNO3. What is the pH if you neglected
  activities?

pH -logH
17
Finally

• Calculate the pH of a solution that contains 0.1
  M Acid and 0.01 M conjugate base
• Calculate the pH of a solution containing 0.1 M
  Acid and 0.05 M conjugate base.
• Calculate the pH of a solution containing 0.1 M
  Acid and 0.1 M conjugate base.

18
Acid/Base Titrations
19
Titrations

• Titration Curve always calculate equivalent
  point first
• Strong Acid/Strong Base
• Regions that require different calculations
• B/F any base is added
• Half-way point region
• At the equivalence point
• After the equivalence point

20
Strong Acid/Strong Base

• 50 mL of 0.02000 M KOH
• Titrated with 0.1000 M HBr
• First -find Volume at equivalence
• M1V1 M2V2
• (0.050 L)(0.02000M) 0.1000 V
• V 10.0 mL

21
Strong Acid/Strong Base

• 50.00 mL of 0.02000 M KOH
• Titrated with 0.1000 M HBr
• Second find initial pH
• pH - logAH -log H
• pOH -logAOH -log OH-
• pH 12.30

22
Strong Acid/Strong Base

• 50 mL of 0.02000 M KOH
• Titrated with 0.1000 M HBr
• Third find pH at mid-way volume
• KOH (aq) HBr (aq) -gt H2O (l) KBr(aq)

Before After
0.001000 mol
0.0006000 mol
0.000400 mol
0 mol
0.0006000 mol
0.0006000 mol
pH 11.8
23
Strong Acid/Strong Base

• 50 mL of 0.02000 M KOH
• Titrated with 0.1000 M HBr
• Fourth find pH at equivalence point

• KOH (aq) HBr (aq) -gt H2O (l) KBr(aq)

Before After
0.001000 mol
0.0010000 mol
0 mol
0 mol
0.0010000 mol
0.0010000 mol
pH 7.0
24
Strong Acid/Strong Base

• 50 mL of 0.02000 M KOH
• Titrated with 0.1000 M HBr
• Finally find pH after equivalence point

12 ml

• KOH (aq) HBr (aq) -gt H2O (l) KBr(aq)

Before After
0.001000 mol
0.001200 mol
0 mol
0.0002000 mol
0.0010000 mol
pH 2.5
25
(No Transcript)
26
(No Transcript)
27
Titration of WEAK acid with a strong base
28
(No Transcript)
29
Titration of a weak acid solution with a strong
base.

• 25.0 mL of 0.1000M acetic acid
• Ka 1.8 x 10-5
• Titrant 0.100 M NaOH
• First, calculate the volume at the
  equivalence-point
• M1V1 M2V2
• (0.0250 L) 0.1000 M 0.1000 M (V2)
• V2 0.0250 L or 25.0 mL

30
Titration of a weak acid solution with a strong
base.

• 25.0 mL of 0.1000M acetic acid
• Ka 1.8 x 10-5
• Titrant 0.100 M NaOH
• Second, Calculate the initial pH of the acetic
  acid solution

31
Titration of a weak acid solution with a strong
base.

• 25.0 mL of 0.1000M acetic acid
• Ka 1.8 x 10-5
• Titrant 0.100 M NaOH
• Third, Calculate the pH at some intermediate
  volume

32
Titration of a weak acid solution with a strong
base.

• 25.0 mL of 0.1000M acetic acid
• Ka 1.8 x 10-5
• Titrant 0.100 M NaOH
• Fourth, Calculate the pH at equivalence

33
Titration of a weak acid solution with a strong
base.

• 25.0 mL of 0.1000M acetic acid
• Ka 1.8 x 10-5
• Titrant 0.100 M NaOH
• Finally calculate the pH after the addition 26.0
  mL of NaOH

34
(No Transcript)