Salt are generally prepared by action between acid and base. Salt is a neutral substance which possesses neither acidic nor basic property nor it shows no effect on indicators such as litmus paper. Salts need high heat for melting and boiling. Electrolysis takes place in salty solution which means decomposition of an electrolyte by the passage of electric current.
Copper oxide is a metallic oxide (a salt) which, when treated with sulphuric acid produces copper sulphate or complete replacement of hydrogen of an acid by a metal or electropositive radical.
H2SO4 + NaOH = NaHSO4 + H2O (partial replacement)
H2SO4 + 2NaOH = NaHSO4 + 2H2O (complete replacement)
When salts are dissolved in water, these ionize giving positively and negatively charged ions other than hydrogen ion (H+) or, hydroxyl (OH-) in solution. In some cases hydrogen and hydroxyl ions may also be present in addition to other positive or negative ions, the presence of which is essential characteristics of salt.
General methods of Preparation of salts:
1. All nitrates are soluble.
2. All salts of sodium, potassium and ammonium are soluble.
3. All carbonates are insoluble except sodium, potassium and ammonium carbonates.
4. All sulphates are soluble in water except for barium and lead sulphates which are insoluble and calcium sulphate which is only very soluble.
5. All chlorides are soluble in water except silver and lead chloride.
Some soluble salts are given below:
Chemical name | Molecular formula | Common name |
Sodium chloride Sodium carbonate Sodium sulphate Magnesium sulphate | NaCl Na2CO3.10H2O Na2SO4.10H2O MgSO4.7H2O | Common salt Washing soda Glauber’s salt Epsom salt |
Some salts are insoluble in water. They have industrial importance. Insoluble salts are used to produce different colors. Some are listed below:
Common name of color | Molecular formula | Color produced |
Lead sulphate Copper carbonate Lead carbonate Zinc chromate Titanium dioxide | PbSO4 CuCO3 PbCO3 ZnCrO3 TiO2 | White Green White Yellow white |
Uses of Salts:
Salt | Common name | Uses |
Sodium carbonate Potassium nitrate Magnesium sulphate Sodium chloride Ammonium chloride | Washing soda Saltpeter Epson salt Common salt | Softening water, making glass Fertilizer, gunpowder Medicine Cooking fertilizer |
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