Question

How do bases react with the following? Write the equations

1. Non-metallic oxide
2. Ammonium salt
3. Soluble metallic salt
   

Answer 1

Step 1: Since these oxides are acids, when a base reacts with them, a neutralisation reaction takes place yielding salt and water.

The general form of the reaction between a non-metal oxide and a base can be written as,

Non−metal oxide + Base → Salt + Water

Examples-

Base + carbon dioxide,

$2\mathrm{NaOH}+{\mathrm{CO}}_2\to {\mathrm{Na}}_2{\mathrm{CO}}_3+{\mathrm{H}}_2\mathrm{O}$

Base + sulphur trioxide,

$2\mathrm{NaOH}+{\mathrm{SO}}_3\to {\mathrm{Na}}_2{\mathrm{SO}}_4+\mathrm{H}2\mathrm{O}$

Base + phosphorous pentoxide,

$12\mathrm{NaOH}+{\mathrm{P}}_2{\mathrm{O}}_{10}\to 4{\mathrm{Na}}_3{\mathrm{PO}}_4+6{\mathrm{H}}_2$

Step 2: In the ammonium ion,

${\mathrm{NH}}_4^{+}$ , where the fourth hydrogen is connected by a dative covalent bond, and this reacts with a negatively charged ion to form an ammonium salt like ammonium chloride, ammonium sulphate, ammonium nitrate, etc, these ammonium salts readily react with bases to give ammonia gas.

The general form of the reaction between ammonium salt and a base can be written as,

Ammonium salt + Base→​ Salt + Water + Ammonia(g)

Example,

Ammonium chloride + Base,

$2{\mathrm{NH}}_4\mathrm{Cl}+\mathrm{Ca}{\left(\mathrm{OH}\right)}_2\to {\mathrm{CaCl}}_2+2{\mathrm{H}}_2\mathrm{O}+2{\mathrm{NH}}_3\uparrow$

Step 3: Some examples of soluble metallic salts are

$\mathrm{LiBr},\mathrm{LiCl},{\mathrm{MgCl}}_2,{\mathrm{KNO}}_3,{\mathrm{CaCl}}_2,{\mathrm{ZnCl}}_2$

The general form of the reaction between a metallic salt and a base can be written as,

Metallic salt + Base → Salt + Metal hydroxide (ppt.)

This reaction is a displacement reaction.

Example-

${\mathrm{AlCl}}_3+3\mathrm{NaOH}\to 3\mathrm{NaCl}+\mathrm{Al}{\left(\mathrm{OH}\right)}_3\uparrow$

Final Answer:

1. Non-metallic oxides react with a base and result in the formation of a salt with water as a by-product.
2. Ammonium salt reacts with a base and results in the formation of a salt and ammonia gas with water as a by-product.
3. The soluble metallic salt aluminium chloride reacts with the base sodium hydroxide to give sodium chloride and aluminium hydroxide which is a solid precipitate (insoluble).