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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: PFScience on July 20, 2015, 04:00:31 PM

Title: Accurate data for latiicce energy and hydration enthalpy
Post by: PFScience on July 20, 2015, 04:00:31 PM

Hi all

I dont suppose anyone has some accurate figures for the above for NH₄Cl and NH₄NO₃?

I'm tutoring a younger student and am trying to illustrate endothermic reactions in solutions. Most of the figures I can find and/or crunch using Kapustinski's have the ΔH_hyd > ΔH_le (dissociation) which makes it exothermic.

Thanks!

Title: Re: Accurate data for latiicce energy and hydration enthalpy
Post by: mjc123 on July 21, 2015, 06:09:48 AM

From here http://nshs-science.net/chemistry/common/pdf/R-standard_enthalpy_of_formation.pdf I get the following enthalpies of formation:
NH₄Cl (s) -315.4 kJ/mol
NH₄NO₃ (s) -365.1
NH₄+ (aq) -132.8
NO3^- (aq) -206.6
Cl^- (aq) -167.4
These will enable you to work out the heats of solution. I also find (Johnson, Thermodynamic aspects of inorganic chemistry)
NH₄⁺ (g) 619
Cl- (g) -246
but no value for NO₃^- (g)
which will give you lattice and hydration energies for NH₄Cl, but not NH₄NO₃.

Title: Re: Accurate data for latiicce energy and hydration enthalpy
Post by: PFScience on July 23, 2015, 01:04:47 PM

Much appreciated

 :)