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Topic: Enthalpy of Solution with Hess's Law  (Read 809 times)

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Offline rg16

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Enthalpy of Solution with Hess's Law
« on: December 03, 2020, 07:22:42 PM »
Hi! For an experimental investigation I'm doing, I need to find the literature enthalpies of solution of CuCl2 and Cu(NO3)2. I've found literature values for all the other compounds I'm testing except for these copper compounds. I am trying to figure out if I can determine these through Hess's Law, but I'm really confused on what reactions to use and add up.

So far, I just have the reactions written out:
CuCl2 (s) --> CuCl2 (aq), and then the same with the nitrate compound.
I've tried using things like: CuO + 2HCl --> CuCl2 (aq) + H2O, but it doesn't seem to work when I add these reaction equations. Any guidance on which reaction equations to use or any alternative ways to find heat of solution non-experimentally would be appreciated!
Thanks!

Offline mjc123

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Re: Enthalpy of Solution with Hess's Law
« Reply #1 on: December 04, 2020, 05:36:21 AM »
Try looking up enthalpies of formation of the compounds. You should be able to find it for e.g. CuCl2(s); maybe not for CuCl2(aq), but you should find values for Cu2+(aq) and Cl-(aq).

Offline rg16

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Re: Enthalpy of Solution with Hess's Law
« Reply #2 on: December 04, 2020, 04:46:41 PM »
Thanks for replying! So I found the enthalpies of formation for CuCl2 (s) and both the aqueous ions. Now, I just do the sum of products (the aqueous ions) - the sum of reactants/the solid, (multiplying the enthalpy of Cl- by 2) correct? Also, for copper (II) nitrate, I wasn't able to find a heat of formation for it in the solid state in any sort of database; I was only able to find the enthalpy in problems about its decomposition reaction in worksheets posted online from college courses. Would you happen to know of any more reliable place/way I can find that enthalpy of formation? Again, thank you!

Offline mjc123

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Re: Enthalpy of Solution with Hess's Law
« Reply #3 on: December 05, 2020, 05:10:38 PM »
Try this: https://www.update.uu.se/~jolkkonen/pdf/CRC_TD.pdf. I found it googling "copper nitrate enthalpy of formation".

Offline CelticKhemist2000

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Re: Enthalpy of Solution with Hess's Law
« Reply #4 on: December 06, 2020, 12:07:01 AM »
How can you have CuCl2 in solid and aqueous form?

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