CHEMISTRY FORM 4 KSSM CHAPTER 6 ACID, BASE AND SALT Activity 6.7 Investigate the colour of the salts and their solubility in water

1. CHAPTER 6
ACID, BASE AND SALT
PREPARED BY : ESTHER ANNE ANAK RANDI

2. Chapter 6 Acid, Base and Salt
6.1 Role of water in showing acidic and alkaline
properties.
6.2 pH value
6.3 Strength of acids and alkalis
6.4 Chemical properties of acids and alkalis
6.5 Concentration of aqueous solutions
6.6 Standard solution
6.7 Neutralisation
6.8 Salts, crystals and their uses in daily life
6.9 Preparation of salts
6.10 Effect of heat on salts
6.11 Qualitative analysis

3. M
What are the ingredients used to bake a cake?

4. M Can you identify the cations and anions that makes up the
salts above?
Copper (II) ions, Cu2+ Iron(II) ions, Fe2+ Manganese (II) ions, Mn2+
? ions ? ions

5. Qualitative Analysis to Identify Cations and Anions in Salts
• Qualitative analysis of a salt – a technique used to identify the
cations and anions present in a salt by analysing its physical and
chemical properties.
• Steps involved in Qualitative Analysis of Salt :
1. Observation on the physical properties of the salt (Colour, Solubility)
2. Effect of heat on the salt
3. Test for anions and cations
4. Confirmatory tests for cations and anions

6. 1. Observations of the Physical Properties of Salts
• Observing the physical properties of salts such as colour and solubility is the first
step to make inferences on the possibility of the presence of cations and anions in
the salt.
– For example, if you see a blue salt crystal, you can make an inference :
• For solubility test of salts,
– even though it does not confirm the identities of the ions present, it helps us narrow
down the possible identities of the ions present
The salt crystal is blue due to the presence of
copper(II) ions, Cu2+

7. Activity 6.7 Investigate the colour of the salts and their solubility in water
Aim : To investigate the colour of the salts and their solubility in water.
Materials : Solid ammonium nitrate, NH4NO3, solid potassium nitrate,
KNO3 , solid sodium chloride, NaCl, solid calcium carbonate,
CaCO3, solid calcium nitrate, Ca(NO3)2 , solid magnesium
sulphate, MgSO4, solid magnesium carbonate, MgCO3, solid
zinc sulphate, ZnSO4, solid zinc chloride, ZnCl2, solid iron(II)
sulphate, FeSO4, solid iron(III) chloride, FeCl3, solid lead(II)
nitrate, Pb(NO3)2, solid lead(II) chloride, PbCl2, solid lead(II)
sulphate, PbSO4, solid copper(II) sulphate, CuSO4, solid
copper(II) chloride, CuCl2, solid copper(II) nitrate, Cu(NO3)2,
solid copper(II) carbonate, CuCO3 and distilled water
Apparatus : Test tubes, test tube rack, glass rod, spatula and wash
bottle

8. Activity 6.7 Investigate the colour of the salts and their solubility in water
Procedures :
1. Observe and record the colour of each solid salt.
2. Put a little amount of the salt into a test tube. Fill the test tube with
distilled water and stir the mixture.
3. Observe the solubility of the salt and the colour of the solution
formed.
4. Record all observations in Table 6.11.

9. Activity 6.7 Investigate the colour of the salts and their solubility in water
Results :
Type of salt Colour of salt Solubility in water Colour of salt solution
Yes No
Ammonium nitrate, NH4NO3 White / Colourless
Potassium nitrate, KNO3 White / Colourless
Sodium chloride, NaCl White / Colourless
Calcium carbonate, CaCO3 White / Insoluble
Calcium nitrate, Ca(NO3)2 White / Colourless
Magnesium sulphate, MgSO4 White / Colourless
Magnesium carbonate, MgCO3 White / Insoluble
Zinc sulphate, ZnSO4 White / Colourless
Zinc chloride, ZnCl2 White / Colourless

10. Activity 6.7 Investigate the colour of the salts and their solubility in water
Results :
Type of salt Colour of salt Solubility in water Colour of salt solution
Yes No
Iron(II) sulphate, FeSO4 Light green / Light green
Iron(III) chloride, FeCl3 Brown / Brown
Lead(II) nitrate, Pb(NO3)2 White / Colourless
Lead(II) chloride, PbCl2 White / Insoluble
Lead(II) sulphate, PbSO4 White / Insoluble
Copper(II) sulphate, CuSO4 Blue / Blue
Copper(II) chloride, CuCl2 Green / Blue
Copper(II) nitrate, Cu(NO3)2 Blue / Blue
Copper(II) carbonate, CuCO3 Green / Insoluble

11. Activity 6.7 Investigate the colour of the salts and their solubility in water
Interpreting data :
1. Name solid salts that are coloured :
(a) Green
(b) Brown
(c) Blue
(d) White
2. Name green salts that are :
(a) Insoluble in water
(b) Soluble in water to form a blue solution
(c) Soluble in water to form a light green solution

12. Activity 6.7 Investigate the colour of the salts and their solubility in water
Interpreting data :
1. Name solid salts that are coloured :
(a) Green
(a) Iron(II) sulphate, FeSO4, copper(II) carbonate, CuCO3, copper(II) chloride,
CuCl2
(b) Brown
(a) Iron(III) chloride, FeCl3
(c) Blue
(a) Copper(II) sulphate, CuSO4, copper(II) nitrate, Cu(NO3)2
(d) White
(a) Ammonium nitrate, NH4NO3, potassium nitrate, KNO3, sodium chloride,
NaCl, calcium carbonate, CaCO3, calcium nitrate, Ca(NO3)2, magnesium
sulphate, MgSO4 , magnesium carbonate, MgCO3 , zinc sulphate, ZnSO4 ,
zinc chloride, ZnCl2 , lead(II) nitrate, Pb(NO3)2, lead(II) chloride, PbCl2,
lead(II) sulphate, PbSO4

13. Activity 6.7 Investigate the colour of the salts and their solubility in water
Interpreting data :
2. Name green salts that are :
(a) Insoluble in water
(a) Copper(II) carbonate, CuCO3
(b) Soluble in water to form a blue solution
(a) Copper(II) chloride, CuCl2
(c) Soluble in water to form a light green solution
(a) Iron(II) sulphate, FeSO4

14. Activity 6.7 Investigate the colour of the salts and their solubility in water
Discussion :
1. Is the colour of the salt suitable to identify the cation presents in the
salt? Explain.
2. What is the colour of the solution formed when the white salt
dissolves in water?
3. Classify each salt as soluble salts or insoluble salts.
4. What is the operational definition of insoluble salts?

15. Activity 6.7 Investigate the colour of the salts and their solubility in water
Discussion :
1. Is the colour of the salt suitable to identify the cation presents in the
salt? Explain.
No. There are many various salts with the same colour.

16. Activity 6.7 Investigate the colour of the salts and their solubility in water
Discussion :
2. What is the colour of the solution formed when the white salt
dissolves in water?
Colourless

17. Activity 6.7 Investigate the colour of the salts and their solubility in water
Discussion :
3. Classify each salt as soluble salts or insoluble salts.
Soluble salts :
Iron(II) sulphate, FeSO4, copper(II) chloride, CuCl2, Iron(III) chloride,
FeCl3, copper(II) sulphate, CuSO4, copper(II) nitrate, Cu(NO3)2,
ammonium nitrate, NH4NO3, potassium nitrate, KNO3, sodium
chloride, NaCl, calcium nitrate, Ca(NO3)2, magnesium sulphate,
MgSO4, zinc sulphate, ZnSO4, zinc chloride, ZnCl2, lead(II) nitrate,
Pb(NO3)2
Insoluble salts :
calcium carbonate, CaCO3, magnesium carbonate, MgCO3, lead(II)
chloride, PbCl2, lead(II) sulphate, PbSO4 , copper(II) carbonate,
CuCO3

18. Activity 6.7 Investigate the colour of the salts and their solubility in water
Discussion :
4. What is the operational definition of insoluble salts?
The salt that remains as solid in distilled water after the salt is put
in a test tube containing distilled water.

19. Activity 6.7 Investigate the colour of the salts and their solubility in water
• All white soluble salts dissolve in water to form colourless salt
solutions.
• Salts form coloured solutions due to the presence of ions in transition
elements.
• For examples :

20. Activity 6.7 Investigate the colour of the salts and their solubility in water
• Table 6.12 shows the colour of some salts in the solid state and in
aqueous solution.

21. Activity 6.7 Investigate the colour of the salts and their solubility in water
• Figure 6.49 shows the example on the qualitative analysis of a solid X
which is green in colour and three possible results.