Question.1: Explain Arrhenius concept of acid & base.
Ans.: According to Arrhenius concept, the acids and bases are defined as follows:
Acid: An acid is regarded as a hydrogen containing substance, which gives off hydrogen ion (H+) dissociating in the aqueous solutions. Actually an acid produces H30+ (hydronium ion) in water. Arrhenius concept is based upon ionic dissociation of compound in water.
Thus HCl is an acid because it produces H+ ion in water:
HCl + H2O → H+(aq) + Cl–(aq)
Example: HCI, HNO3, H2SO4, CH3-COOH etc.
In general, HA + H2O → H+(aq) + A–(aq)
acid Base: A base is regarded as a hydroxyl group-containing compound, which gives off hydroxyl ions (OH–) when dissociated in the aqueous solution. NaOH is a base because it yields OH– ion in water.
NaOH + H2O → Na+(aq) + OH–(aq)
Example: NaOH, Ca(OH)2, NH4OH etc.
In general, BOH + H2O → B+(aq) + OH–(aq)
Thus according to Arrhenius concept, Acids give H+ ions in water, bases give OH– ions in water |