1. Qualitative Analysis Cations
Internal Assessment 2.1- part one

2. Record your results clearly
First step:
add
2 drops of dilute NaOH(aq)
Record your results clearly

3. add 2 drops of dilute NaOH solution.
no precipitate Na+

4. add 2 drops of dilute NaOH solution. add excess NaOH solution
white precipitate forms Al3+, Zn2+, Pb2+, Mg2+, Ba2+
add excess NaOH solution
precipitate disappears Al3+, Zn2+, Pb2+
precipitate remains Mg2+, Ba2+

5. Mg2+(aq) + 2 OH(aq)  Mg(OH)2(s)
Equations needed for Merit and Excellence
white precipitate forms Al3+, Zn2+, Pb2+, Mg2+, Ba2+
Mg2+(aq) OH(aq)  Mg(OH)2(s)
Add the equations for the rest of the cations.
Equations needed for Excellence
precipitate disappears Al3+, Zn2+, Pb2+
Zn(OH)2(s) OH(aq)  [Zn(OH)4]2(aq)
Zn2+(aq) OH(aq)  [Zn(OH)4]2(aq)
Add the equations for Al3+ and Pb2+ .

6. add dilute H2SO4 solution
Is it Mg2+ or Ba2+?
precipitate remains Mg2+, Ba2+
New solution in a clean test tube!!!!
add dilute H2SO4 solution
colourless solution Mg2+
white precipitate Ba2+
Equation needed for Merit and Excellence
SO42(aq) + Ba2+(aq)  BaSO4(s)

7. add 2 drops, then excess NH3 solution
precipitate disappears Al3+, Zn2+, Pb2+
NH3 is a base
NH3 provides OH- ions in solution
Write down the 3 equations for the precipitates.
New solution in a clean test tube!!!!
add 2 drops, then excess NH3 solution
Equations needed for Merit and Excellence
white precipitate forms and disappears, Zn2+
Equation needed for Excellence
white precipitate forms Al3+, Pb2+
Zn(OH)2(s) + 4 NH3(aq)  [Zn(NH3)4]2+ (aq) + 2 OH (aq)
Zn2+(aq) NH3(aq)  [Zn(NH3)4]2+(aq)

8. add dilute H2SO4 solution
Is it Al3+ or Pb2+?
white precipitate forms Al3+, Pb2+
New solution in a clean test tube!!!!
add dilute H2SO4 solution
Equations needed for Merit and Excellence
colourless solution Al3+
white precipitate Pb2+
Pb2+(aq) + SO42(aq)  PbSO4(s)

10. add 2 drops of dilute NaOH solution.
green precipitate forms Fe2+
Equation needed for Merit and Excellence
Write down the equation for this reaction.

11. add 2 drops of dilute NaOH solution. add 2 drops KSCN solution
orange precipitate forms Fe3+
add 2 drops KSCN solution
dark red solution confirms Fe3+
New solution in a clean test tube for confirmatory test
Equation needed for Merit and Excellence
Fe3+(aq) OH(aq)  Fe(OH)3(s)
Equation needed for Excellence
Fe3+(aq) + SCN(aq)  [FeSCN]2+(aq)

12. The complex ion is: [Cu(NH3)4]2+ add 2 drops of dilute NaOH solution.
blue precipitate forms Cu2+
add 2 drops, then excess NH3 solution
blue precipitate then deep blue solution
Cu2+
New solution in a clean test tube for confirmatory test
Clear solution !!!!
Write down the equation for this reaction.
The complex ion is:
[Cu(NH3)4]2+
Equation needed for Merit and Excellence
Write down the equation for this reaction.
Equation needed for Excellence

13. The complex ion is: [Ag(NH3)2] + add 2 drops of dilute NaOH solution.
brown precipitate forms Ag+
add 2 drops, then excess NH3 solution
brown precipitate then colourless solution Ag+
New solution in a clean test tube for confirmatory test
Clear solution !!!!
Write down the equation for this reaction.
The complex ion is:
[Ag(NH3)2] +
Equation needed for Merit and Excellence
Write down the equation for this reaction.