Neutralization

NEUTRALIZATION (neutralization or averaging), in the chemical sense—the process of destroying the properties of a free acid by adding a base or destroying the properties of a free base by adding an acid. During neutralization, heat is released, and two new substances are formed: water and salt of the corresponding acid and base. The formation of water is the moment that determines and directs the neutralization reaction, and is explained as follows: both acid and base, when dissolved in water, dissociate electrolytically: the acid giving H+ and the corresponding anion; the alkali giving OH- and the corresponding cation. Between these four ions, the reaction proceeds in the direction of forming a compound between H+ of the acid and OH- of the base, which give water—a compound that dissociates negligibly (dissociation constant at 18°=10^-14), while the remaining free ions lead to the formation of salt: K+ + OH- + H+ + Cl- = H₂O + K+ + Cl-. A truly neutral solution is one in which the concentration of H+ and OH- is equal and equal to the concentration of these ions in pure water. The endpoint of neutralization is usually determined using indicator solutions or indicator papers. Since different indicators change color at various pH values, a solution that is neutral with respect to one indicator may be acidic with respect to another and alkaline with respect to a third. Therefore, expressions such as neutral to congo, to litmus, or alkaline to litmus, to phenolphthalein, etc., are used. When neutralizing strong acids and bases, a truly neutral solution can only be obtained by finishing with weak acids or bases, thereby obtaining a buffer solution (see Buffer properties) with the desired concentration of H-ions. In precise work, the endpoint of neutralization should be determined by the electrometric method (see Gas chain). Neutralization forms the basis of acidimetry and alkalimetry (see). For processes of neutralization in the body—see. Active reaction, Alkalosis, Acidosis, Buffer properties.