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Solubility of Ionic substances

The equation from what I have learnt is:

Delta H solution= Sum of delta H hydration - dHlattice formation

I keep getting these kind of questions wrong :erm:

E.g.

http://qualifications.pearson.com/content/dam/pdf/International%20Advanced%20Level/Chemistry/2013/Exam%20materials/WCH04_01_que_20140113.pdf

Question 4
Do you know how to draw Hess cycles for these types of questions?



Original post by Dinaa
The equation from what I have learnt is:

Delta H solution= Sum of delta H hydration - dHlattice formation

I keep getting these kind of questions wrong :erm:

E.g.

http://qualifications.pearson.com/content/dam/pdf/International%20Advanced%20Level/Chemistry/2013/Exam%20materials/WCH04_01_que_20140113.pdf

Question 4
Original post by Poooky
Do you know how to draw Hess cycles for these types of questions?


Same as for any other process:

NaCl(s) ----> Na+(aq) + Cl-(aq) ΔHsolution

NaCl(s) ---> Na+(g) + Cl-(g) ----> Na+(aq) + Cl-(aq) (i) ΔHlattice enthalpy --- > (ii) ΔHhydration
Original post by charco
Same as for any other process:

NaCl(s) ----> Na+(aq) + Cl-(aq) ΔHsolution

NaCl(s) ---> Na+(g) + Cl-(g) ----> Na+(aq) + Cl-(aq) (i) ΔHlattice enthalpy --- > (ii) ΔHhydration


I was trying to get OP to work through it :smile: I thought if she could draw it out, she'd be able to see where she went wrong- usually it's either using the wrong signs or forgetting about balancing the equation ie that there are 2 Cl-'s involved in the reaction- hopefully that helps @Dinaa
Original post by Poooky
I was trying to get OP to work through it :smile: I thought if she could draw it out, she'd be able to see where she went wrong- usually it's either using the wrong signs or forgetting about balancing the equation ie that there are 2 Cl-'s involved in the reaction- hopefully that helps @Dinaa


I'm sorry, I misread your post ...

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