Question

Complete the reaction:
$HCl + NaOH \to$
a) $NaCl + {H_2}O$
b) $NaCl + H + OH$
c) $NaCl + {H_2}$
d) $Na + Cl + {H_2}O$

Answer 1

Neutralisation reaction is the kind of reaction where acids and bases are neutralised in the reaction media. On the reaction of acids with metals the evolution of hydrogen gas takes place. It can be detected by the pop sound. This is a characteristic reaction of acid and base.

Complete step by step solution:
Acids are the substances which on dissolution in water give ${H^ + }$ ion. For e.g. $HCl$ when dissolved in water acts as a very strong acid, ${H_2}S{O_4}$ etc.
The Bases are the substances which on dissolution in water give $O{H^ - }$ ion. For e.g. $NaOH$ when dissolved in water acts as a very strong base, etc.
Metals on reacting with sulphuric acid release hydrogen gas and form salts. This is a characteristic reaction of metals. The hydrogen gas released gives a pop sound when came in contact with fire.
$\begin{gathered} Metal + Acid \to Salt + Hydrogen Gas \uparrow \\\ Mg + 2HCl \to MgC{l_2} + {H_2} \uparrow \\\ \end{gathered}$
Neutralisation reactions are the reactions where acids and bases react to form salt and water. For example-
$\begin{gathered} Acid + Base \to Salt + Water \\\ HCl + NaOH \to NaCl + {H_2}O \\\ \end{gathered}$
As hydrochloric acid has a single proton and thus it can be neutralised by a base which has at least a single basic ion as sodium hydroxide has only one basic ion.
The acids which have two protons can be balanced by sodium hydroxide but the consumed concentration will be twice as required by acid of single proton. For e.g.
${H_2}S{O_4} + 2NaOH \to N{a_2}S{O_4} + 2{H_2}O$
$HCl + NaOH \to NaCl + {H_2}O$
From the above reaction it can be concluded that to neutralise one mole of sulphuric acid, two moles of sodium hydroxide is consumed if we measure the strengths by titration whereas to neutralise one mole of hydrochloric acid only one mole of sodium hydroxide is used.
Hence the product we got are $NaCl,{H_2}O$
$\therefore$ Correct option is (a).

Note:
In a neutralisation reaction, neutralisation is the condition when no ${H^ + }$ or $O{H^ - }$ ions are freely left in solution. The properties of the ions can be determined by volumetric titrations, conductometric titrations, potentiometric titrations etc.