# Hydrogen - Types and Methods of Preparation

Table of Content:

## Introduction to Hydrogen

Hydrogen is smallest of all elements atomic number 1, atomic mass is 1. It is inflammable gas and less soluble in water. It acts as fuel with high calorific value.

### Isotopes of Hydrogen

Hydrogen shows three isotopes:

1. Protium $\left( _{1}^{1}H \right):$ It has zero neutrons
2. Deuterium $\left( _{1}^{2}H \right):$ It has one neutrons
3. Tritium $\left( _{1}^{3}H \right):$ It has two neutrons.

### Position of Hydrogen in Periodic Table

Hydrogen resembles I A group Alkali metals and VII-A group halogens.

#### Resemblance with I A Group

1. Hydrogen and elements of I A group shows same outer configuration ns1
2. During electrolysis, Hydrogen gas is liberated at Cathode.
3. Oxidation state of Alkali metals and hydrogen is +1.

#### Resemblance Of Hydrogen With Halogens

1. Both Hydrogen and Halogen are non-metals.
2. Hydrogen has a higher electronegativity (2.1).
3. It has high Ionisation potential.
4. It accepts one electron easily and forms hydride ion (H) like a halide ion (X).

Thus, hydrogen resembles more with halogen than alkali metals. Hence the position of hydrogen is not justified in the periodic table.

## Types of Hydrogen

Molecular hydrogen occurs in two isomeric forms.

1. Ortho-Hydrogen: In this type two proton nuclear spins are aligned parallel.
2. Para-Hydrogen: In this type two proton nuclear spins are aligned antiparallel.

### Methods of Preparation of Hydrogen

#### By the Electrolysis of Water

$2{{H}_{2}}0\rightarrow{electric\,\,current}2{{H}_{2}}\left( g \right)+{{O}_{2}}\left( g \right)$

#### By the Action of Acids on Strong Electro Positive Metals

$2Na+{{H}_{2}}S{{O}_{4}}\rightarrow{{}}N{{a}_{2}}S{{O}_{4}}+{{H}_{2}}$

$2K+2HCl\rightarrow{{}}2KCl+{{H}_{2}}$

#### By the Action of Water on Strong Electro Positive Metals

$2Na+2{{H}_{2}}O\rightarrow{{}}2NaOH+{{H}_{2}}$

#### By the Action of Alkali on Amphoteric Metals like Al, Zn etc

$\underset{\left( Hot\,\And \,Concentrated \right)}{\mathop{6NaOH}}\,+2Al\rightarrow{{}}\underset{Sod.\,Aluminate}{\mathop{2N{{a}_{3}}Al{{o}_{3}}}}\,+3{{H}_{2}}$

$Zn+2NaOH\rightarrow{{}}\underset{Sod.\,Zincate}{\mathop{N{{a}_{2}}Zn{{O}_{2}}}}\,+{{H}_{2}}$

#### Large Scale Production of Hydrogen

$C{{H}_{4}}+{{H}_{2}}O\rightarrow[100-1000{}^\circ C]{3-25\,bar}10+2{{H}_{2}}$

$CO+{{H}_{2}}O\rightarrow{{}}C{{O}_{2}}+{{H}_{2}}$

## Properties Of Hydrogen

### Physical Properties Of Hydrogen

1. Colourless, odourless, neutral gas.
2. Less soluble in water.
3. Highly inflammable.
4. Burns with a blue flame.
5. Very low boiling points.

### Chemical Properties Of Hydrogen

#### Action with Oxygen

${{H}_{2}}+\frac{1}{2}{{O}_{2}}\rightarrow[\Delta ]{200{}^\circ C}{{H}_{2}}O$

#### Action with Metals

$2Na+{{H}_{2}}\rightarrow[\Delta ]{350{}^\circ C}\underset{Sodium\,hydride}{\mathop{2NaH}}\,$

#### Action with Halogens

${{H}_{2}}+{{F}_{2}}\rightarrow{dark}2HF$

${{H}_{2}}+C{{l}_{2}}\rightarrow{sun\,\,light}2HCl$

${{H}_{2}}+B{{r}_{2}}\rightarrow{350{}^\circ C}2HBr$

${{H}_{2}}+{{I}_{2}}2HI$

#### Reducing Action

$W{{O}_{3}}+3{{H}_{2}}\rightarrow{{}}3{{H}_{2}}O+W$

#### Nuclear Fusion Reactions

It takes place in stars.

$4_{1}^{1}H\rightarrow{{}}\underset{Helium}{\mathop{_{2}^{4}He}}\,+\underset{Position}{\mathop{2{{_{+1}^{0}}^{e}}}}\,+27M\,e\,V$

## Uses Of Hydrogen

1. In the preparation of Ammonia.
2. As a fuel in preparation of fuel gases like water gas.
3. As a reducing agent in metallurgy
4. In Nuclear fusion, a large amount of energy is released in stars.