Question

Potassium and Sodium are not used for reaction with dilute HCl or dilute Sulphuric acid in the laboratory preparation of hydrogen gas. Explain Why?

Answer 1

Hydrogen gas can be obtained by reacting alkali metals with acids but we can’t use this method in the laboratory. Hydrogen is a special atom of the periodic table. It behaves like alkali metals as well as like halogens. Due to its dual nature, its electronic configuration is $1{S^1}$

Complete step by step answer:
Hydrogen atoms exist as Single positive ions means ${H^ + }$. Hydrogen manufactures oxides, halides, Sulphides with reacting seriously Oxygen, Halogen, Sulphur. This behaviour equates hydrogen with alkali metals. Hydrogen manufactures covalent compounds by reacting other elements. This behaviour equates hydrogen with halogens.
Hydrogen gas can be prepared by many methods. Some methods are showing here.
1.By reacting crystal zinc with dilute Hydrochloric acid.
$Zn + 2HCl \to ZnC{l_2} + {H_2}$
2. By reacting Zn, Al or Sn with aqueous base like NaOH.
$Zn + 2NaOH\xrightarrow{\Delta }N{a_2}Zn{O_2} + {H_2}$ or
$2Al + 2{H_2}O + 2NaOH\xrightarrow{\Delta }2NaAl{O_2} + 3{H_2}$
3.By electrolysis of slightly acidic water using platinum electrode ${H_2}$ can be prepared.
$2{H_2}O(l)\xrightarrow[{slightly - acid/base}]{{electrolysis}}2{H_2}(g) + {O_2}(g)$
We have more methods to prepare hydrogen gas.
Hydrogen gas is also produced by reacting Potassium or Sodium with dilute Hydrochloric acid or diluting Sulphuric acid in the laboratory.
$K + dil.HCl \to KCl + \dfrac{1}{2}{H_2}(g)$
$2Na + dil.{H_2}S{O_4} \to N{a_2}S{O_4} + {H_2}(g)$
These reactions are highly exothermic. Means a lot of energy is released in these explosives. So, this cannot be done in the laboratory. So, Potassium and Sodium are used for reaction with dilute hydrochloric acid or dilute Sulphuric acid for the preparation of hydrogen gas in the laboratory.

Note:
Potassium and Sodium are very reactive metals. These metals react with acids very quickly and explosively. So by reacting K and Na with acid-producing hydrogen is very harmful and heat is explored in lots of amounts. We can not use this method.