born-haber calculations confusion (arrows and signs)
suppose i've got everything except step 3 - the bond dissociation of F2(g)
the mark scheme's equation goes like this:
–DHf + DHsub + DHi + ½DHdiss + DHea – DHL = 0
and then we'd have to rearrange etc. etc.
however I don't understand why DHea (step 4) is + (positive - ADDED) in the equation when the arrow is obviously pointing DOWNWARDS the same as –DHf (Route 1) and – DHL (step 5)?
I don't think it's a typo in the mark scheme, so what's the reason please?
Looks wrong to me - each side must be of equal ''height'' in energy terms:
LHS = - RHS
-ΔHf + ΔHsub + ΔHi + 0.5ΔHdiss = -(ΔHEA + ΔHlatt)
thus -ΔHf + ΔHsub + ΔHi + 0.5ΔHdiss + ΔHEA + ΔHlatt = 0
LHS = - RHS
-ΔHf + ΔHsub + ΔHi + 0.5ΔHdiss = -(ΔHEA + ΔHlatt)
thus -ΔHf + ΔHsub + ΔHi + 0.5ΔHdiss + ΔHEA + ΔHlatt = 0
(edited 10 years ago)
Quick Reply
Related discussions
- energetics a level chem help!
- Hess law and combustion
- enthalpy change of solution
- Help urgent maths
- Chemistry help pleaseee !!!! 🙏🙏🙏
- Edexcel A-Level Chemistry Paper 1 Core Inorganic and Physical Chemistry [Exam Chat]
- Knowing when you can turn right
- enthalpy change for combustion?
- Enthaly Change and Hess's Law
- Calculations of reactants based on equations? o_o;
- AQA A Level Chemistry Paper 3 7405/3 - 23 Jun 2022 [Exam Chat]
- Physics question confusion
- chemistry a level ocr question
- A level chem ocr
- gcse chemistry help
- enthalpy changes
- Edexcel A-Level Chem Paper 1 Advanced Inorganic and Physical Chemistry [Exam Chat]
- enthalpy change of sol
- Chemistry olympiad
- As level chemistry
Latest
Trending
Last reply 1 week ago
Im confused about this chemistry question, why does it form these productsTrending
Last reply 1 week ago
Im confused about this chemistry question, why does it form these products
