CHEMISTRY FORM 2
- 1.1 Structure of the atom
- 1.2 Atomic Number and Mass Number
- 1.3 Isotopes
- 1.4 Energy levels and electron arrangement
- 1.5 Development of the Periodic Table
- 1.6 Relative Atomic Mass and Isotopes
- 1.7 Ion Formation
- 1.8 Chemical Formulae
- 1.9 Chemical Equations
- 2.1 Alkali metals (Group I elements)
- 2.2 Alkali Earth Metals (Group II elements)
- 2.3 Halogens (Group VII elements)
- 2.4 Noble gases (Group VIII elements)
- 2.5 Properties and Trends Across the Periodic Table
- 3.1 Bond
- 3.2 Ionic bond
- 3.3 Giant ionic structure
- 3.4 Covalent bond
- 3.5 Co-ordinate bond
- 3.6 Molecular structures
- 3.7 Giant covalent structures
- 3.8 Metallic Bond
- 3.9 Types of bond across a period
- 3.10 Oxides of elements in Period 3
- 3.11 Chlorides of Period 3 elements
- 4.1 What is a salt?
- 4.2 Types of salt
- 4.3 Solubility of salts in water
- 4.4 Methods of preparing salts
- 4.4.1 Reacting a Metal with an Acid
- 4.4.2 Reacting an Acid with a Base (Neutralization)
- 4.4.3 Reacting an Acid with a Carbonate (or hydrogencarbonate of metal)
- 4.4.4 Combining elements Directly (Direct Combination of elements)
- 4.4.5 Precipitation (Double decomposition)
- 4.5 Action of heat on salts
- 4.6 Uses of salts
- 5.1 Electrical conduction
- 5.2 Electrical conductivity of molten substances
- 5.3 Electrical conductivity of substances in aqueous state
- 5.4 Electrolysis
- 5.5 Applications of electrolysis
- 6.1 Allotropes of carbon
- 6.2 Chemical properties of carbon
- 6.3 Carbon (IV) oxide
- 6.4 Carbon (II) oxide (CO)
- 6.5 Large scale production of sodium carbonate and sodium hydrogencarbonate
- 6.6 Effect of carbon (II) oxide and carbon (IV) oxide on the environment
- 6.7 Carbon cycle
Salts: Reacting an Acid with a Carbonate (or hydrogencarbonate of metal)
4.0 Salts
4.4.3 Reacting an Acid with a Carbonate (or hydrogencarbonate of metal)
Observe the video showing preparation of salts from acids and carbonates.
Questions 4.4.3
You are required to prepare copper (II) chloride crystals by reacting a suitable acid with a carbonate. Explain how you would go about this. Include an equation for the reaction. Describe the observations made during the reaction.
Answers to Questions 4.4.3
Except for the carbonates of sodium, potassium and ammonium ions, the state symbol of carbonates is (s) because they are insoluble. The hydrogencarbonates react in a similar way; but their state symbol is (aq) because they are soluble. Figure 4.4.3 shows the appearance of copper (II) chloride.
Figure 4.4.3(a) Copper (II) chloride crystals
Hydrated salts
Most of the salts that crystallyze do so by combining with some definite amount of water, called water of crystallization. Copper (II) sulphate, for example, crystalizes with 5 molecules of water. The formula of hydrated copper (II) sulphate is therefore CuSO4.5H2O. Table 4.4.3 shows more examples of hydrated salts and the number of molecules of water involved.
Figure 4.4.3(b) Hydrated salts
Some anhydrous salts slowly absorb water vapour from the air and become hydrated. They are called hygroscopic salts. An example is anhydrous copper (II) sulphate. Others absorb so much water and turn into solution when exposed to air. They are called deliquescent salts. An example is iron (III) chloride.
Still others lose water of crystallization and are called efflorescent salts. Hydrated sodium carbonate is an example. Efflorescent salts normally burst plastic bottles open or slowly overflow under the lid because of this.