The Student Room Group

Avogadro constant

I'm doing an OCR salter's past paper (June 2005) on Natural Resources and there's a question about Avogadro constant which I thought I understood.

I did the question etc. but when I compared with the answer I was completely wrong and when I tried out the example answer it comes out wrong too. So either the mark scheme is wrong, or I'm being completely thick so please help!

The bond enthalpy of the C-F bond is +467 kJ mol-1. Calculate the minimum energy in joules needed to break a single C-F bond.

Avogadro constant, L=6.02 x 10^23 mol-1


Example answer: 467 x 6.02 x 10^23 x 1000 = 7.75 x 10^-19 J
My answer: 467000 x 6.02 x 10^23 = 2.81 x 10^29 J
the question asks you for the energy required to break ONE BOND ONLY.

The bond energy is quoted per mole of bonds so you must DIVIDE the energy by Avocado's number.
Reply 2
thank you....all the revision is making my brain fuzzy!

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