KSSM Chemistry Analysis

1. Chemical Analysis of Salts
A) Effects of Heat on Salts
1. Some salts undergo decomposition when heated.
2. Decomposed salts might show a change in colour and sometimes they may also
release gases.
3. The ease of breaking down determines the thermal stability of salts.
4. The harder it is to break down a salt using heat, the more thermally-stable the salt is.
5. The tables below show the effect of heat on carbonate and nitrate salts.
• Carbonate salts of very reactive metals do not decompose upon heating
• Carbonate salts of less reactive metals breaks down to form metal oxides and
CO2
• Carbonate salts of unreactive metals breaks down to form their respective
metals, CO2 and O2.
• Ammonium carbonate decomposes to form ammonia gas, CO2 and H2O.

2. • Nitrate salts of very reactive metals decompose upon heating to produce
metal nitrites and O2.
• Nitrate salts of less reactive metals breaks down to form metal oxides, NO2 and
O2.
• Nitrate salts of unreactive metals breaks down to form their respective metals,
NO2 and O2.
• Ammonium nitrate decomposes to form nitrous oxide/dinitrogen monoxide,
N2O and H2O.
6. Most sulphate salts do not decompose.
7. Most chloride salts also do not decompose except for ammonia chloride which
decomposes upon heating to produce ammonia and hydrogen chloride:

3. B) Physical properties of salts
1. To identify salts, we must first be able to observe its physical properties.
2. Examples of these physical properties are solubility in water and colour.
C) Anion Tests
1. In an aqueous solution, ions can move freely.
2. There are two types of ions: anions (negatively-charged) and cations (positively-
charged)
3. We can identify common anions using tests.
4. Examples are shown below.

4. D) Cation Tests
1. Cations can also be identified using tests.
2. Usually, sodium hydroxide or ammonia is added into solutions containing the cation.

5. Summary:

6. E) Other Tests
1. Confirmatory tests for Fe2+ and Fe3+ ions.
2. Confirmatory tests for Lead, Pb2+ and ammonium, NH4
+ ions