Question

Identify the compound X on the basis of the reactions given below. Also, write the name and chemical formulae of A, B and C.

Answer 1

Identifying the compound X:

Reaction 1:

• Zinc metal reacts with Sodium hydroxide to form Sodium zincate along with the evolution of hydrogen gas.
• It is also known as a displacement reaction in which a less reactive element is replaced by a more reactive element to form a new compound.

$\underset{\mathrm{Spdium}\mathrm{Hydroxide}}{2\mathrm{NaOH}\left(\mathrm{aq}\right)}+\underset{\mathrm{Zinc}}{\mathrm{Zn}}\left(\mathrm{s}\right)\to \underset{\mathrm{Sodium}\mathrm{Zincate}}{{\mathrm{Na}}_2{\mathrm{ZnO}}_2\left(\mathrm{s}\right)}+\underset{\mathrm{Dihydrogen}}{{\mathrm{H}}_2\left(\mathrm{g}\right)}$

• So, the compound A is Sodium zincate (${\mathrm{Na}}_2{\mathrm{ZnO}}_2$)

Reaction 2:

• When an acid reacts with a base, it will lead to the formation of salt and water.
• Such reactions are known as neutralization reactions.
• The neutralization reaction between hydrochloric acid and sodium hydroxide can be represented as:

$\underset{\mathrm{Sodium}\mathrm{Hydroxide}}{\mathrm{NaOH}\left(\mathrm{aq}\right)}+\underset{\mathrm{Hydrochloric}\mathrm{acid}}{\mathrm{HCl}\left(\mathrm{aq}\right)}\to \underset{\mathrm{Sodium}\mathrm{Chloride}}{\mathrm{NaCl}\left(\mathrm{aq}\right)}+\underset{\mathrm{Water}}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}$

• The compound B is Sodium chloride ($\mathrm{NaCl}$)

Reaction 3:

• Sodium hydroxide reacts with a weak acetic acid, it will lead to the formation of basic salt sodium acetate and water.
• The balanced chemical reaction can be written as:

$\underset{\mathrm{Sodium}\mathrm{Hydroxide}}{\mathrm{NaOH}\left(\mathrm{aq}\right)}+\underset{\mathrm{Acetic}\mathrm{acid}}{{\mathrm{CH}}_3\mathrm{COOH}\left(\mathrm{aq}\right)}\to \underset{\mathrm{Sodium}\mathrm{acetate}}{{\mathrm{CH}}_3\mathrm{COONa}\left(\mathrm{aq}\right)}+\underset{\mathrm{Water}}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}$

• The compound C is Sodium acetate (${\mathrm{CH}}_3\mathrm{COONa}$)
• The compound X is Sodium hydroxide ($\mathrm{NaOH}$)

Therefore, compounds A, B, and C are Sodium zincate (${\mathrm{Na}}_2{\mathrm{ZnO}}_2$), Sodium chloride ($\mathrm{NaCl}$), Sodium acetate (${\mathrm{CH}}_3\mathrm{COONa}$) and compound X is Sodium hydroxide ($\mathrm{NaOH}$).