Hydrides
Chapter Name : Hydrogen |
Sub Topic Code : 102_11_09_05_03 |
Topic Name : Hydrides |
|
Sub Topic Name : Metallic Or Non-Stoichiometric Hydrides |
|
Introduction
In transition elements there are small empty spaces among the atoms.
Hydrogen gas adsorbs in these empty spaces to produce Interstitial hydrides
which are known as metallic hydrides.
Pre-Requisites:
Hot
swapping, Non-stoichiometric
Activity:
Most of these hydrides are good conductors of electricity in solid
state.
Real Life Question:
What is the difference between absorption and
adsorption?
Key Words / FlashCards
| Key Words | Definitions (pref. in our own words) |
|---|---|
| Non-stoichiometric | Meaning basically that the fraction of H atoms to the metals are not fixed. Nonstoichiometric compounds have a variable composition. |
| Hot swapping | Hot swapping and Hot plugging are terms used to describe the functions of replacing the system components without shutting down the system. |
Learning aids / Gadgets
| Gadgets | How it can be used |
|---|---|
| Water, drain clog removal (containing sodium hydroxide) + aluminium foil | When water is added to a drain clog removal liquid in the presence of aluminium ( using aluminium foil) , hydrogen gas is liberated. This is an exothermic reaction. |
Real life uses :
Metallic hydrides can be used to store hydrogen
especially in cars working on fuel cells.
Places to visit :
Chemistry
lab
Practical examples around us
| Examples | Explainations |
|---|---|
| Hydrogen as a fuel | Hydrogen is commonly used in the petroleum and chemical industries and is also widely used for many physics and engineering applications such as welding or as a coolant. |
What you learn in Theory:
•
Elements
of groups 3, 4, 5 (d-block) and f-block elements form metallic hydrides. In
group 6, only Cr forms hydride (CrH).
Metals
of group 7, 8, 9 do not form hydrides. This region of periodic table from group
7 to group 9 is known as hydride gap. Examples of hydrides of group 3 to 5 are,
ScH2, YH2, YH3, LaH2, LaH3,
TiH2, ZrH2, HfH2, VH, VH2, NbH, NbH2,
TaH
What you learn in Practice:
The density of these hydrides is lower than those of metals from which
they are formed since the crystal lattice expands due to inclusion oh H2.