
 Originally Posted by 
isuzurover
					 
				 
				What I was trying to point out is that the number of atoms of each is not the only issue. e.g. Acetylene C2H2 has the highest energy content on a weight basis, bacause it is a very dense molecule.
Burning olefins with H2 gas is not the same as burning parrafins.
			
		 
	 
 Not that simple either - the available energy per molecule is the difference between the bond energy of the molecule you start with and the molecule(s) you finish with. Even assuming you finish with CO2 and water, the atoms present in the fuel are not a good measure of this - the reason acetylene has a high energy content is only partly because it is dense (as a first approximation the density of a gas is proportional to the molecular weight and as hydrocarbon gases go acetylene is the almost same density as ethane or ethylene - the reason acetylene has more energy available is that it has a triple unsaturated bond between the two carbons, where ethane (a paraffin) has all saturated bonds and ethylene a double unsaturated bond.
John
				
			 
			
		 
			
				
			
				
			
			
				John
JDNSW
1986 110 County 3.9 diesel
1970 2a 109 2.25 petrol
			
			
		 
	
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