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Help on this one chem multiple choice Question

Okey
(edited 12 years ago)
Reply 1
any of you guys take chemistry?
Complete combustion involves converting all the C to CO2 and all the H to H2O. Hence for every C in the molecule you need 2 oxygen atom (or one O2 molecule) and for each H you need half an oxygen atom. You have 8 molecules of O2 which is 16 O atoms. So to work out how many O atoms you need for each just double the number of C atoms, add half the number of H atoms and subtract any O atoms already present. And you get:-
A) = (5*2) + (12/2) - 1 = 15 (wrong!)
B) = (6*2) + (10/2) - 1 = 16 (correct)
C) = (6*2) + (12/2) - 1 = 17 (wrong)
D) = (6*2) + (12/2) = 18 (wrong)

Hence the answer is B, simples!

MP

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