Year 12s: what will be the first way you research your future options? >>

aqa chem5 hardhardhard

http://filestore.aqa.org.uk/subjects/AQA-CHEM5-QP-JAN13.PDF
1c)iii
i get the 0.5 cl2 + 1.3 f2 bit
but i dont get why 3 cl-f was subtracted from that?
thanksss

Reply 1

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Reply 2

BJack

The enthalpy of formation is the enthalpy change going from your starting materials to your products. It's not just a case of working out how much energy it takes to break those initial bonds; you also need to include the energy you get back when the new bonds are formed.