Chemistry

General Properties of Bases :
1. The solutions of bases in water give a soapy touch. When dissolved in water they produce hydroxide ions (OH^–) in solution.|

2. They turn red litmus paper blue.
Take some soap solution in a test tube. Dip the tip of a red litmus paper into it. You will see that red litmus paper turns blue. This indicates that the soap solution contains a base.
3. They react with acids to produce salt and water.
NaOH + HCI → NaCl + H₂O
2KOH + H₂SO₄ → CuSO₄ + 2H₂O
Cu(OH)₂ + H₂SO₄ → CuSO₄ + 2H₂O
In these reactions, the acid and the base neutralize each other. Therefore, these reactions are called neutralization reactions.
Thus, a neutralization reaction may be defined as a reaction between an acid and a base, producing salt and water.
This neutralization reaction may be explained as follows. You know, all acids provide H⁺ ions and all bases provide OH^– ions in aqueous solution. Let us see what happens when HCl and NaOH react together. -
HCl + NaOH → NaCl + H₂O
or H⁺ + Cl^– + Na⁺ + OH^– → Na⁺ + Cl^– + H₂O
or H⁺ + OH^– → H₂O
Thus, during neutralization of an acid with a base or vice versa H⁺ ions (from acid) and (OH^–) ions (from base) combine to produce H₂O molecules.
4. The oxides which produce acids in aqueous solutions are called acidic oxides which are usually the oxides of nonmetals. Acidic oxides react with bases to give salts and water.

5. When a base is heated with an ammonium salt, ammonia gas, another salt and water are produced. For example, when sodium hydroxide is heated with ammonium chloride, the products formed are sodium chloride, water and ammonia gas.

Ammonia gas is recognized by its pungent smell.
6. Bases react with certain salts to produce another salt and another base. For example, when NH₄OH is added to a solution of Al₂(SO₄)₃, (NH₄)₂SO₄ and Al(OH)₃ are produced.