July 9, 2008

Composition of Coal

Sir, While fully accepting the fundamentals of Dr Paddy Ryan's atomic weight calculations for carbon-dioxide (Mailbox, June 18), for many reasons, I am uneasy about the translation of molecular mass directly into gravitational mass.

I would need to see the scientific reasoning before being convinced in either direction.

Notwithstanding I take issue with the chemistry and mathematics of his recent letter.

His calculations assume 1 tonne of coal equals 1 tonne of carbon, meaning coal is solely 100 percent pure carbon. But, coal is not a unique chemical substance and is neither pure nor just carbon.

Each deposit is chemically different and contains from about 30 percent carbon for lignites through to around 90 percent for anthracites.

If it were possible, generic coal, might look something like C16- H40-O8-N4-S2- P, but don't quote me.

He also claims that every carbon atom in coal is oxidised only into carbon- dioxide.

That assumption ignores the production of any other carbon- oxides and any other carbon compounds and substances, such as carbon- monoxide, carbon particulate, soot and ash, let alone any hydrates, nitrates, sulphates or phosphates that may or may not be formed.

I therefore consider his conclusion, that 1 tonne of coal wholly oxidises into 3.66 tonnes of carbon-dioxide, to be fatally flawed and thus invalid.


Stoke, July 3.

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