Chemistry - A Molecular Science

Chapter 10 Solutions

Example 10.11

Write net equations for the precipitation reactions in example 10.9.

a) Solutions of FeSO

and KOH 4

The precipitate is Fe(OH)

, so 2OH 2

1- ions are required for each Fe

2+ ion.

Fe

2+ + 2OH

1-^ →

Fe(OH)

(^2)
b) Solutions of Pb(ClO
) 42
and CuSO
(^4)
The precipitate is PbSO

. There is 1:1 ratio of ions, so the net equation is 4

Pb

2+ + SO

2- 4

→

PbSO

(^4)
c) Solutions of K
PO 3
and CoCl 4
(^2)
The precipitate is Co
(PO 3
) 42
, so 3Co
2+ and 2PO
3- 4
are required.
3Co
2+ + 2PO
3-^4
→
Co
(PO 3
) 42
Example 10.12 Write net equations for the reactions occurring when solutions of the following substances are mixed. Indicate ‘no reaction’ if no precipitate is expected to form. a) Potassium iodide + lead nitrate
1+K

• I
  1- + Pb
  2+ + NO
  1-^3
  1
  2

1. No reaction because KNO

is soluble by Rules 1 and 2. 3

2. PbI

precipitates by Rule 3. 2

Net reaction: Pb

2+ + 2I

1-^ →

PbI

(s). 2

b) Sodium phosphate + silver nitrate

Na

1+ + PO

3- 4

+ Ag

1+ + NO

1- 3

1

2

1. No reaction because NaNO

is soluble by Rules 1 and 2. 3

(^)

2. Ag

PO 3

precipitates by Rule 5. 4

Net reaction: 3Ag

1+ + PO

3-^4

→

Ag

PO 3

(s). 4

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