Hess's law ?

Question

I know that the answer is suppose to me around 88 kj/ mol. I just cannot figure out how the different equations cross out, or if there is another way to do this.

ChemTeam · Answer

The data that you provide has a major mistake. The lattice energy for KCl should be a negative value, not a positive.

If you search for the LE of KCl, you will be able to verify this

The solution to your problem can be found here:

https://www.chemteam.info/Thermochem/HessLawIntro1b.html

Look at example #9, to the bottom of the file.

I recommend you tell someone about the above mistake. Feel free to express it as you finding it or express it as a question (Shouldn't this be a negative value? Help me, I'm a poor confused student!). Skip mentioning that someone (me!) told you this on the Internet because I'm just a guy on the Internet. What the heck do I know? I could be a dog for all your teacher knows.

Roger the Mole · Answer

This URL

https://www.clutchprep.com/chemistry/practice-problems/68374/what-is-the-enthalpy-of-sublimation-for-k-in-kj-mol-given-lattice-energy-of-kcl-

seems to address this problem, but it goes way beyond Hess's law.

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Hess's law ?

2 Answers