The essentials

Here is a brief description of hydrogen.

• Standard state: gas at 298 K (the lightest gas known)


• Colour: colourless


• Classification: Non-metallic


• Availability:
  

  Hydrogen is available commercially in pressurised tanks.

  
  

This sample is from The Elements Collection, an attractive and safely packaged collection of the 92 naturally occurring elements that is available for sale.

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 (H₂O) 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 (Hindenburg).

The lifting agent for the ill fated Hindenberg ballooon was hydrogen rather than the safer helium. The image below is the scene probably in a way you have not seen it before. This is a "ray-traced" image reproduced with the permission of Johannes Ewers, the artist, who won first place with this image in the March/April 1999 Internet Raytracing Competition. For details of ray-tracing you can't beat the POV-Ray site.

Nearing Zero cartoon included by kind permission of Nick Kim.

Isolation

Here is a brief summary of the isolation of hydrogen.

In the laboratory, small amounts of hydrogen gas may be made by the reaction of calcium hydride with water.

CaH₂ + 2H₂O → Ca(OH)₂ + 2H₂

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 + H₂SO₄ → FeSO₄ + H₂

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.

CH₄ + H₂O (1100°C) → CO + 3H₂

C(coke) + H₂O (1000°C) → CO + H₂

In both these cases, further hydrogen may be made by passing the CO and steam over hot (400°C) iron oxide or cobalt oxide.

CO + H₂O → CO₂ + H₂

_{source - elements world !!!}