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Name: Monique
Status: educator
Grade: 9-12
Country: Canada
Date: Summer 2010
Question:
I am working on a marking guide for a grade 12 chemistry correspondence course. Stuck on the following problem: A saturated long-chain hydrocarbon undergoes complete combustion. Analysis of the reaction products reveals that 7 molecules of carbon dioxide and 14 molecules of water vapour are produced for every molecule of the hydrocarbon that burns. Write a balanced equation for this reaction. I cannot make the hydrogens balance!


Replies:
This is more appropriate to a math class permutations and combinations, than chemistry. You have been pitched a curve ball because cyclic compounds have not been excluded. Since this medium does not make graphics easily, but here are my efforts:

The compounds 1,3 - dimethyl cyclopentane has the stoichiometry of C7H14. There are many other examples that fill that criterion.

Vince Calder


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