Question

Complete the reaction:
\[{\text{sodium hydroxide}} + {\text{hydrochloric acid}} \to \]
A.\[{\text{Sodium Chloride}} + {\text{Water}}\]
B.\[{\text{sodium chloride}} + {\text{Water}} + {\text{Heat}}\]
C.\[{\text{Water}} + {\text{Heat}}\]
D.\[{\text{Sodium}} + {\text{Heat}}\]

Answer 1

Hint: When strong acids like hydrochloric acid are made to react with strong bases like sodium hydroxide, then neutral salts such as sodium chloride and water are formed. This is an example of exothermic reaction.

Complete step by step answer:
- The reaction in which heat is released is known as an exothermic reaction like neutralization reaction. On the other hand, reaction in which heat is absorbed is known as endothermic reaction like conversion of graphite to diamond and etc.
- The reaction between an acid and a base is known as neutralization reaction, as the effect of a base is nullified when mixed with acid or vice versa. In general, a neutralization reaction can be written as: \[{\text{Acid}} + {\text{base}} \to {\text{salt}} + {\text{water}}\].
- The process of dissolving an acid or a base in water is a highly exothermic reaction as heat is evolved during the reaction. Hydrogen ions are produced by hydrochloric acid in the presence of water. The separation of hydrogen ion and chloride ion from hydrochloric acid molecules cannot occur in the absence of water: \[{\text{HCl}} + {{\text{H}}_2}{\text{O}} = {{\text{H}}^ + } + {\text{C}}{{\text{l}}^ - }\] as hydrogen ion cannot exist alone but exist after combining with water molecules.
- Similarly hydroxide ions are produced by base like sodium hydroxide in water as follow: \[{\text{NaOH}} + {{\text{H}}_2}{\text{O}} = {\text{N}}{{\text{a}}^ + } + {\text{O}}{{\text{H}}^ - }\], as when sodium hydroxide and hydrochloric acid are allowed to mix in an aqueous solution; sodium chloride as salt ill be formed with the liberation of heat.
- The chemical equation will be as follow: \[{\text{NaOH}} + {\text{HCl}} = {\text{NaCl}} + {{\text{H}}_2}{\text{O}} + {\text{heat}}\].

Thus, the correct option is B.

Note:
Sodium chloride or \[{\text{NaCl}}\] is formed from sodium ion from sodium hydroxide base and chloride ion from hydrochloric acid. The attraction between sodium and chloride ions in sodium chloride salt is ionic attraction. Mostly salts like sodium chloride, potassium chloride are highly soluble in water which are made up from strong acid and strong base.