Page 20 - Pharmaceutical analytical chemistry |

Conjugate acids and bases
When an acid gives up a proton, a conjugate base is formed that is
capable of accepting a proton as:

Acid1 ↔ Base1 + Proton
Here, Acid1 and Base1 represent a conjugate acid-base pair.
Similarly, every base produces its conjugate acid as:

Base2 + Proton ↔ Acid2
When these two half-reactions are combined, the result is an acid-base or
neutralization reaction.

Acid1 + Base2 ↔ Base1+Acid2
3) Lewis theory

An acid is a substance that can accept an election pair, and a base is a
substance that can donate an election pair. The latter frequently contains
oxygen or nitrogen atom as the electron donor.

H+ + :NH3 → H : NH3+
AlCl3 + :OR2→ Cl3Al : OR2

H+ + :OH2 → H : OH2+
H+ + :OH- → H : OH

 The chemical equilibrium

The reactions used in analytical chemistry are seldom complete. Instead,
they proceed to a state of chemical equilibrium in which the ratio of
concentration of reactants and products is constant. As the reaction
proceeds, the concentration of the reactants decreases, and so does the
rate at which they react. On the other hand, the concentration of the
products increases and so does the rate at which they react. Eventually, a
state of equilibrium is reached, wherein the rate of forward reaction
between the reactants A and B is balanced by the rate of backward
reaction between the products C and D.

A+B↔C+D

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