Neutralization

All neutralization reactions can be broadly summarized by the following equation:

Using a hydrogen ion to represent an acid and a hydroxide ion to represent a base, a neutralization reaction may also be expressed as

The formation of the salt is omitted in this generalized type of equation because the salt ions do not undergo a chemical change during a neutralization reaction. Neutralization reactions usually take place in water. An example of a strong acid and a strong base reacting in water-indicated by (aq), meaning aqueous-is the reaction between two corrosive solutions, sodium hydroxide (NaOH) and hydrochloric acid (HCl), to form table salt (NaCl) and water. The table salt remains dissolved in the water and exists as ions of sodium (Na⁺) and chloride (Cl^-).

Neutralization does not occur only in solution. Acidic and basic gases can undergo neutralization reactions, as in the reaction between the two corrosive gases ammonia (NH₃) and hydrogen chloride (HCl) to form the solid salt ammonium chloride (NH₄Cl).

Weak acids and bases will also undergo neutralization reactions. The reaction of the acetic acid (HAc) in vinegar with the sodium bicarbonate (NaHCO₃) in baking soda produces water, sodium ions (Na⁺), acetate ions (Ac^-), and carbon dioxide gas (CO₂). The reaction between baking soda and acids in dough creates bubbles of carbon dioxide that make cakes and cookies rise and become fluffy.