Berkeley Review Gen. Chem Question.

[Mces97]

According to a chart the pKa of acetic acid is 4.74 and the pKa of p-Nitro benzoic acid is 7.18. Can someone explain to my why 1.0M acetic acid does not have a higher boiling point than 1.0M p-Nitro benzoic acid. I thought Acetic acid is a stronger acid because of the lower pKa value.
... Nevermind guys, I figured out my mistake. I was looking at the wrong compound. Not sure how to delete this post, but the pKa of the benzoic acid should have been written 3.40

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[muhali3]

I think there should be a difference. But I think it is so small as to be negligible.

I think since only a very very small amount of either dissociates, you can disregard their dissociation and leave out the vant hoff factor.

(someone correct me if I'm wrong)

 

[BerkReviewTeach]

According to a chart the pKa of acetic acid is 4.74 and the pKa of p-Nitro benzoic acid is 7.18. Can someone explain to my why 1.0M acetic acid does not have a higher boiling point than 1.0M p-Nitro benzoic acid. I thought Acetic acid is a stronger acid because of the lower pKa value.
... Nevermind guys, I figured out my mistake. I was looking at the wrong compound. Not sure how to delete this post, but the pKa of the benzoic acid should have been written 3.40

For some reason everyone makes that same table reading error of looking at the wrong nitro-compound. It must be something about the way our minds track data in tables. Like the classic example of...

Paris
in the
the spring​

where people naturally read it as "Paris in the spring."