Solution Stoichiometry (Lecture 2)

1
Solution Stoichiometry(Lecture 2)

• Mass concentration Dilution and volumetric
  analysis

2
What will I learn?

• What is mass concentration?(and how is it
  related to molar concentration?)
• What is dilution?
• What is volumetric analysis? (or titration?)
• How to calculate an unknown concentration in a
  volumetric analysis problem?

3
Other Concentration Units

• Sometimes, concentration can be expressed in mass
  per unit volume

4
Other Concentration Units

• Sometimes, concentration can be expressed in mass
  per unit volume
• Units gdm-3

5
Other Concentration Units

• Sometimes, concentration can be expressed in mass
  per unit volume
• Concentration (in gdm-3) can be converted to
  molar concentration via the equation

6
Example 1

• 2.00 g of NaOH is dissolved in water to give a
  final volume of 150.0 cm3.
• Calculate the concentration (in gdm-3) of the
  NaOH solution formed

7
Example 1

• 2.00 g of NaOH is dissolved in water to give a
  final volume of 150.0 cm3.
• Calculate the concentration (in moldm-3) of the
  solution above

8
Example 1

• 2.00 g of NaOH is dissolved in water to give a
  final volume of 150.0 cm3.
• Calculate the concentration (in moldm-3) of the
  solution above

9
Example 1

• 2.00 g of NaOH is dissolved in water to give a
  final volume of 150.0 cm3.
• Calculate the concentration (in moldm-3) of the
  solution above

10
Example 1

• 2.00 g of NaOH is dissolved in water to give a
  final volume of 150.0 cm3.
• Calculate the concentration (in moldm-3) of the
  solution above

11
Dilution

• Dilution is the process of adding more solvent to
  a solution

Remains constant
decreases
increases
12
Example 1

• 10.0 cm3 of a NaOH solution of concentration
  1.500 moldm-3 was diluted to 250 cm3 using
  distilled water. Calculate the concentration of
  NaOH after dilution.

Rearranging,
13
Example 1

• 10.0 cm3 of a NaOH solution of concentration
  1.500 moldm-3 was diluted to 250 cm3 using
  distilled water. Calculate the concentration of
  NaOH after dilution.

14
Example 1

• 10.0 cm3 of a NaOH solution of concentration
  1.500 moldm-3 was diluted to 250 cm3 using
  distilled water. Calculate the concentration of
  NaOH after dilution.

15
Example 1

• 10.0 cm3 of a NaOH solution of concentration
  1.500 moldm-3 was diluted to 250 cm3 using
  distilled water. Calculate the concentration of
  NaOH after dilution.

16
Example 1

• 10.0 cm3 of a NaOH solution of concentration
  1.500 moldm-3 was diluted to 250 cm3 using
  distilled water. Calculate the concentration of
  NaOH after dilution.

17
Example 1

• 10.0 cm3 of a NaOH solution of concentration
  1.500 moldm-3 was diluted to 250 cm3 using
  distilled water. Calculate the concentration of
  NaOH after dilution.

18
Example 1

• 10.0 cm3 of a NaOH solution of concentration
  1.500 moldm-3 was diluted to 250 cm3 using
  distilled water. Calculate the concentration of
  NaOH after dilution.

19
Example 2

• A concentrated solution of H2SO4 has a
  concentration of 3.35 moldm-3. What volume of
  this acid is required to prepare 250.0 cm3 of
  0.130 moldm-3 H2SO4 solution?

20
Example 2

• A concentrated solution of H2SO4 has a
  concentration of 3.35 moldm-3. What volume of
  this acid is required to prepare 250.0 cm3 of
  0.130 moldm-3 H2SO4 solution?

21
Example 2

• A concentrated solution of H2SO4 has a
  concentration of 3.35 moldm-3. What volume of
  this acid is required to prepare 250.0 cm3 of
  0.130 moldm-3 H2SO4 solution?

22
Example 2

• A concentrated solution of H2SO4 has a
  concentration of 3.35 moldm-3. What volume of
  this acid is required to prepare 250.0 cm3 of
  0.130 moldm-3 H2SO4 solution?

Rearranging,
23
Example 2

• A concentrated solution of H2SO4 has a
  concentration of 3.35 moldm-3. What volume of
  this acid is required to prepare 250.0 cm3 of
  0.130 moldm-3 H2SO4 solution?

24
Example 2

• A concentrated solution of H2SO4 has a
  concentration of 3.35 moldm-3. What volume of
  this acid is required to prepare 250.0 cm3 of
  0.130 moldm-3 H2SO4 solution?

25
Example 2

• A concentrated solution of H2SO4 has a
  concentration of 3.35 moldm-3. What volume of
  this acid is required to prepare 250.0 cm3 of
  0.130 moldm-3 H2SO4 solution?

26
Example 2

• A concentrated solution of H2SO4 has a
  concentration of 3.35 moldm-3. What volume of
  this acid is required to prepare 250.0 cm3 of
  0.130 moldm-3 H2SO4 solution?

27
Dilution

• Useful formulae for dilution

28
Dilution

• Useful formulae for dilution

29
Volumetric analysis

• A quantitative analysis (vs qualitative analysis)
• Analysis gt calculation / manipulation of the
  results to obtain meaningful data
• Volumetric analysis gt accurate measurement of
  volume is required

30
Volumetric analysis
31
Volumetric analysis
32
Volumetric analysis
33
Volumetric analysis

• End point is the point in the titration when the
  indicator undergoes a sharp colour change.
• Equivalence point is the point when
  stoichiometric amounts / volume of reactants have
  been mixed
• The two points are not the same
• However, an ideal indicator is one where the
  equivalence point and end point is very close to
  each other
• (and a sharp colour change occurs when a small
  extra amount of reactant has been added)

34
Calculations in VA

• Similar to that encountered before (in normal
  stoichiometry calculations)
• Difference concentration and reacting volumes
  are now involved

35
Number of moles
Titration volume
mass (m)
number of moles (n)
number of particles (N)
volume (V)
36
Calculations in VA

• Given

since
37

• Example 120.0 cm3 of a solution of barium
  hydroxide, Ba(OH)2, of unknown concentration was
  placed in a conical flask and titrated with a
  solution of hydrochloric acid which had a
  concentration of 0.0600 moldm-3. The volume of
  the acid required was 25.0 cm3. Calculate the
  molar concentration of the barium hydroxide.

Balanced equation
Given c and V
c??
Given V
38

• Example 120.0 cm3 of a solution of barium
  hydroxide, Ba(OH)2, of unknown concentration was
  placed in a conical flask and titrated with a
  solution of hydrochloric acid which had a
  concentration of 0.0600 moldm-3. The volume of
  the acid required was 25.0 cm3. Calculate the
  molar concentration of the barium hydroxide.

Balanced equation
39

• Example 120.0 cm3 of a solution of barium
  hydroxide, Ba(OH)2, of unknown concentration was
  placed in a conical flask and titrated with a
  solution of hydrochloric acid which had a
  concentration of 0.0600 moldm-3. The volume of
  the acid required was 25.0 cm3. Calculate the
  molar concentration of the barium hydroxide.

Balanced equation
40

• Example 120.0 cm3 of a solution of barium
  hydroxide, Ba(OH)2, of unknown concentration was
  placed in a conical flask and titrated with a
  solution of hydrochloric acid which had a
  concentration of 0.0600 moldm-3. The volume of
  the acid required was 25.0 cm3. Calculate the
  molar concentration of the barium hydroxide.

Balanced equation
From equation
41

• Example 120.0 cm3 of a solution of barium
  hydroxide, Ba(OH)2, of unknown concentration was
  placed in a conical flask and titrated with a
  solution of hydrochloric acid which had a
  concentration of 0.0600 moldm-3. The volume of
  the acid required was 25.0 cm3. Calculate the
  molar concentration of the barium hydroxide.

Balanced equation
42

• Example 120.0 cm3 of a solution of barium
  hydroxide, Ba(OH)2, of unknown concentration was
  placed in a conical flask and titrated with a
  solution of hydrochloric acid which had a
  concentration of 0.0600 moldm-3. The volume of
  the acid required was 25.0 cm3. Calculate the
  molar concentration of the barium hydroxide.

Balanced equation
43

• Example 120.0 cm3 of a solution of barium
  hydroxide, Ba(OH)2, of unknown concentration was
  placed in a conical flask and titrated with a
  solution of hydrochloric acid which had a
  concentration of 0.0600 moldm-3. The volume of
  the acid required was 25.0 cm3. Calculate the
  molar concentration of the barium hydroxide.

Balanced equation
44

• Example 120.0 cm3 of a solution of barium
  hydroxide, Ba(OH)2, of unknown concentration was
  placed in a conical flask and titrated with a
  solution of hydrochloric acid which had a
  concentration of 0.0600 moldm-3. The volume of
  the acid required was 25.0 cm3. Calculate the
  molar concentration of the barium hydroxide.

Balanced equation
45

• Example 120.0 cm3 of a solution of barium
  hydroxide, Ba(OH)2, of unknown concentration was
  placed in a conical flask and titrated with a
  solution of hydrochloric acid which had a
  concentration of 0.0600 moldm-3. The volume of
  the acid required was 25.0 cm3. Calculate the
  molar concentration of the barium hydroxide.

Balanced equation
46

• Example 120.0 cm3 of a solution of barium
  hydroxide, Ba(OH)2, of unknown concentration was
  placed in a conical flask and titrated with a
  solution of hydrochloric acid which had a
  concentration of 0.0600 moldm-3. The volume of
  the acid required was 25.0 cm3. Calculate the
  molar concentration of the barium hydroxide.

Balanced equation
ALTERNATIVELY
47

• Example 120.0 cm3 of a solution of barium
  hydroxide, Ba(OH)2, of unknown concentration was
  placed in a conical flask and titrated with a
  solution of hydrochloric acid which had a
  concentration of 0.0600 moldm-3. The volume of
  the acid required was 25.0 cm3. Calculate the
  molar concentration of the barium hydroxide.

Balanced equation
?
48

• Example 120.0 cm3 of a solution of barium
  hydroxide, Ba(OH)2, of unknown concentration was
  placed in a conical flask and titrated with a
  solution of hydrochloric acid which had a
  concentration of 0.0600 moldm-3. The volume of
  the acid required was 25.0 cm3. Calculate the
  molar concentration of the barium hydroxide.

Balanced equation
?
49

• Example 120.0 cm3 of a solution of barium
  hydroxide, Ba(OH)2, of unknown concentration was
  placed in a conical flask and titrated with a
  solution of hydrochloric acid which had a
  concentration of 0.0600 moldm-3. The volume of
  the acid required was 25.0 cm3. Calculate the
  molar concentration of the barium hydroxide.

Balanced equation
?
50

• Example 120.0 cm3 of a solution of barium
  hydroxide, Ba(OH)2, of unknown concentration was
  placed in a conical flask and titrated with a
  solution of hydrochloric acid which had a
  concentration of 0.0600 moldm-3. The volume of
  the acid required was 25.0 cm3. Calculate the
  molar concentration of the barium hydroxide.

Balanced equation
?
51

• Example 2What volume of NaOH of concentration
  0.500 moldm-3 is required to neutralise 22.50
  cm3 of 0.262 moldm-3 sulphuric acid?

Balanced equation
?
52

• Example 2What volume of NaOH of concentration
  0.500 moldm-3 is required to neutralise 22.50
  cm3 of 0.262 moldm-3 sulphuric acid?

Balanced equation
?
53

• Example 2What volume of NaOH of concentration
  0.500 moldm-3 is required to neutralise 22.50
  cm3 of 0.262 moldm-3 sulphuric acid?

Balanced equation
?
54

• Example 2What volume of NaOH of concentration
  0.500 moldm-3 is required to neutralise 22.50
  cm3 of 0.262 moldm-3 sulphuric acid?

Balanced equation
?
55

• Example 2What volume of NaOH of concentration
  0.500 moldm-3 is required to neutralise 22.50
  cm3 of 0.262 moldm-3 sulphuric acid?

Balanced equation
?
56

• Example 3Calculate the volume of nitric acid of
  concentration 0.200 moldm-3 required to react
  completely with 4.0 g of copper(II) oxide.

Balanced equation
Given mass
v??
Given c
57

• Example 3Calculate the volume of nitric acid of
  concentration 0.200 moldm-3 required to react
  completely with 4.0 g of copper(II) oxide.

Balanced equation
58

• Example 3Calculate the volume of nitric acid of
  concentration 0.200 moldm-3 required to react
  completely with 4.0 g of copper(II) oxide.

Balanced equation
59

• Example 3Calculate the volume of nitric acid of
  concentration 0.200 moldm-3 required to react
  completely with 4.0 g of copper(II) oxide.

Balanced equation
?
60

• Example 3Calculate the volume of nitric acid of
  concentration 0.200 moldm-3 required to react
  completely with 4.0 g of copper(II) oxide.

Balanced equation
?
61

• Example 3Calculate the volume of nitric acid of
  concentration 0.200 moldm-3 required to react
  completely with 4.0 g of copper(II) oxide.

Balanced equation
?
Rearranging,
62

• Example 3Calculate the volume of nitric acid of
  concentration 0.200 moldm-3 required to react
  completely with 4.0 g of copper(II) oxide.

Balanced equation
?
63

• Example 3Calculate the volume of nitric acid of
  concentration 0.200 moldm-3 required to react
  completely with 4.0 g of copper(II) oxide.

Balanced equation
?
64

• Example 3Calculate the volume of nitric acid of
  concentration 0.200 moldm-3 required to react
  completely with 4.0 g of copper(II) oxide.

Balanced equation
?
65
What will I learn?

• What is mass concentration?(and how is it
  related to molar concentration?)
• What is dilution?
• What is volumetric analysis? (or titration?)
• How to calculate an unknown concentration in a
  volumetric analysis problem?

66
End of Lecture 2

• Often greater risk is involved in postponement
  than in making a wrong decision Harry A Hopf