1. Solubility rules: Answers to lab

2. X Br – Cl – CO32– NO3 – OH – PO43– SO32– SO42– Ag+ Al3+ Ba2+ Ca2+ Co2+
30/09/99
Br –
Cl –
CO32–
NO3 –
OH –
PO43–
SO32–
SO42–
Ag+ X
Al3+
Ba2+
Ca2+
Co2+
Cu2+
Fe3+ K+
Na+
Ni2+
NH4+

3. Answers 1 - 8 Alkali metals (IA) 2. NH4+ NO3– 4. Br –, Cl –, SO42–
30/09/99
Alkali metals (IA) NH4+
NO3– Br –, Cl –, SO42–
NO3– Na+ or K+ or NH4+
Ag3PO4 AlPO4 Ba3(PO4)2
Ca3(PO4)2 Co3(PO4)2 Cu3(PO4)2
FePO4 Ni3(PO4)2
Ca(NO3)2 Soluble rule 2
FeCl3 Soluble rule 3
Ni(OH)2 Insoluble rule 5
AgNO3 Soluble rule 2
BaSO4 Insoluble rule 4
CuCO3 Insoluble rule 6

4. Answer 9 You have a mixture of Ba2+, Pb2+, Cu2+, Na+
30/09/99
You have a mixture of Ba2+, Pb2+, Cu2+, Na+
Which can be precipitated without the others?
Use Cl –, Br –, or I – to precipitate Pb2+ (rule 3)
Filtering leaves Ba2+, Cu2+, Na+
Use SO42– to precipitate Ba2+ (rule 4)
Filtering leaves Cu2+, Na+
Use OH – (rule 5), or any of PO43–, CO32–, SO32–, S2– (rule 6) to precipitate Cu2+
Since all Na+ compounds are soluble, this will stay in solution

5. Determining net ionic reactions
30/09/99
Determining net ionic reactions
Step 1: Write formula for reactants and products using valences. Products are determined by switching +ve and –ve.
Step 2: Determine if any products are insoluble (use solubility rules). Note: all reactants must be soluble (i.e. aq) in order to mix.
If all products are aqueous: “no reaction”
Step 3: Balance the equation
Step 4: Write the ionic equation
Step 5: Write the net ionic equation
E.g. sodium phosphate + calcium chloride

6. Answers: 10 i) and ii)
30/09/99 i)
(NH4)2S(aq) + Pb(NO3)2(aq)  PbS(s) + 2NH4NO3(aq)
2NH4+(aq) + S2–(aq) + Pb2+(aq) + 2NO3–(aq)  PbS(s) + 2NH4+(aq) + 2NO3–(aq)
Net: S2–(aq) + Pb2+(aq)  PbS(s)
ii) Co(NO3)2(aq) + Na2SO4(aq)  No reaction
Step 1: Write correct formulas
Step 2: Determine if any products are insoluble
Step 3: Balance the equation
Step 4: Write the ionic equation
Step 5: Write the net ionic equation

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Answers: 10 iii) - vi)
30/09/99
iii) AgNO3(aq) + NaI(aq)  AgI(s) + NaNO3(aq)
Ag+(aq) + NO3–(aq) + Na+(aq) + I–(aq)
 AgI(s) + Na+(aq) + NO3–(aq)
Net: Ag+(aq) + I–(aq)  AgI(s)
iv)Al(NO3)3(aq) + 3KOH(aq)  Al(OH)3(s) + 3KNO3(aq)
Al3+(aq) + 3NO3–(aq) + 3K+(aq) + 3OH–(aq)
 Al(OH)3(s) + 3K+(aq) + 3NO3–(aq)
Net: Al3+(aq) + 3OH–(aq)  Al(OH)3(s)
v)Zn(NO3)2(aq) + K2CO3(aq)  ZnCO3(s) + 2KNO3(aq)
Zn2+(aq) + 2NO3–(aq) + 2K+(aq) + CO32–(aq)
 ZnCO3(s) + 2K+(aq) + 2NO3–(aq)
Net: Zn2+(aq) + CO32–(aq)  ZnCO3(s)
vi) KCl(aq) + NaNO3(aq)  No reaction
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