1) Explain the definition of Acid and Bases according to Bronsted- Lowry
Theory, Arrhenius Theory and Lewis Theory?
Bronsted-Lowry:
Acid is a proton (H+) donor and Base is a proton acceptor. Every acid
has a conjugate base and every base has a conjugate acid.
Conjugate base of the acid: When an acid loses a proton, it becomes a conjugate
base of the acid.
Conjugate acid of the base: When a base accepts a proton then it becomes the
conjugate acid of the base.
Arrhenius Theory:
Acid are the substance which release H+ ions when dissolved in water.
Base is the substance which release OH- ions when dissolved in water.
Lewis Theory:
Substances which accept a pair of electrons are known as Acid and the substances
which donate a pair of electrons are known as Base.
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2) What do you mean by a Buffer solution? Explain Acidic and Basic buffer with
an example?
A buffer solution is one that resists the change in pH when small amount of
acid, alkali or water is added to it. Thus pH of the buffer is not changed on
their addition because the components in the buffer can convert the acid or
alkali into weak acid or weak base, which is only slightly dissociated.
Acidic buffer:
An acidic buffer is one that contains a high concentration of an undissociated
weak acid and its conjugate base. It is made by dissolving a weak acid and its
sodium or potassium salt in water. Example: A solution of ethanoic acid and
sodium ethanoate. It has a pH value which is below 7.
Basic buffer:
A basic buffer is one that contains a high concentration of an undissociated
weak base and its conjugate acid. It is made by dissolving a weak base and one
of its soluble salts in water. Example: A solution of ammonia and ammonium
chloride. It has a pH value which is above 7.
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