Which is a stronger acid dichloroacetic acid or fluoroacetic acid????

1 Answer
anor277
Oct 7, 2017

How else would we find out but by examining #pK_a# for #"dichloracetic acid"#, and for #"fluoroacetic acid"#?

Explanation:

This site quotes #pK_a=1.35# for #"dichloroacetic acid"#. And this site quotes #pK_a=2.60# for #"fluoroacetic acid"#. You would typically be given BOTH values and asked to account for the difference in acidity. This is probably an entropy effect in that substitution of the acid by two halogens effectively delocalizes the charge density of the acetate anion.

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