April 21, 2019, 04:52:45 AM
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Topic: Why does acetic acid + NaOH have a larger ∆Hrxn than HCl + NaOH?  (Read 406 times)

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Offline labratattack

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referred here from reddit.

Why does acetic acid + NaOH have a larger ∆Hrxn than HCl + NaOH?

This question comes from general chemistry II lab and is not for a grade (not sure if that matters here or not), but more of a challenge question. Will someone help me understand? Thank you

Offline mjc123

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Re: Why does acetic acid + NaOH have a larger ∆Hrxn than HCl + NaOH?
« Reply #1 on: February 05, 2019, 04:32:18 AM »
What is the actual reaction that happens in HCl + NaOH?
What else happens in AcOH + NaOH?

Offline labratattack

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Re: Why does acetic acid + NaOH have a larger ∆Hrxn than HCl + NaOH?
« Reply #2 on: February 05, 2019, 12:44:09 PM »
HCl and NaOH both completely dissociate and form water plus ions. Acetic acid is a weak acid and doesn’t completely dissociate but NaOH does. So, because acetic acid doesn’t completely dissociate it’s ΔHrxn is greater?

Is that on the right track?

Offline mjc123

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Re: Why does acetic acid + NaOH have a larger ∆Hrxn than HCl + NaOH?
« Reply #3 on: February 06, 2019, 04:34:24 AM »
Yes. Can you write equations for the reactions that occur? Assume (as I assume the question does) that you start with aqueous solutions of the reagents, so you don't have to consider the dissociation of e.g. NaOH - it's already dissociated.

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