hydrogen_28

Hydrogen

Name:Hydrogen

Symbol:H

Atomic Number:1

Atomic Weight:1.00794

Boiling Point:-252.87 �C

Melting Point:-259.14 �C

Density: 11.42 g/cm^3

Electronic Configuration:1

Group Number:1

Group Name:(none). While normally shown at the top of the Group 1

elements in the periodic table, the term "alkaline metal" refers only

to Group 1 elements from lithium onwards.

Description:Gas at room temperature, colorless , non-metallic.

About it:Hydrogen is the lightest element. It is by far the most

abundant element in the universe and makes up about about 90% of the

universe by weight. Hydrogen as water (H[2]O) is absolutely essential

to life and it is present in all organic compounds. Hydrogen gas was

used in lighter-than-air balloons for transport but is far too

dangerous because of the fire risk.The lifting agent for the ill fated

Hindenberg balloon was hydrogen rather than the safer helium.

Isolation

In the laboratory, small amounts of hydrogen gas may be made by the

reaction of calcium hydride with water.

CaH[2] + 2H[2]O -> Ca(OH)[2] + 2H[2]

This is quite efficient in the sense that 50% of the hydrogen produced

comes from water. Another very convenient laboratory scale experiment

follows Boyle's early synthesis, the reaction of iron filings with

dilute sulphuric acid.

Fe + H[2]SO[4] -> FeSO[4] + H[2]

There are many industrial methods for the production of hydrogen and

that used will depend upon local factors such as the quantity required

and the raw materials to hand. Two processes in use involve heating

coke with steam in the water gas shift reaction or hydrocarbons such

as methane with steam.

CH[4] + H[2]O (1100�C) -> CO + 3H[2]

C(coke) + H[2]O (1000�C) -> CO + H[2]

In both these cases, further hydrogen may be made by passing the CO

and steam over hot (400�C) iron oxide or cobalt oxide.