Chemistry Practice Problems Ka and Kb Practice Problems Solution: Which of the following acids has the weakest conju...

Solution: Which of the following acids has the weakest conjugate base? a. 3-chlorobenzoic acid,  Ka = 1.5x10-4b. hypochlorous acid, Ka = 2.9x10-8c. formic acid, Ka = 1.86x10-4d. chloroacetic acid, Ka = 1.26x10-3e. nitrous acid,  Ka = 4.5x10-4

Problem

Which of the following acids has the weakest conjugate base? 

a. 3-chlorobenzoic acid,  Ka = 1.5x10-4

b. hypochlorous acid, Ka = 2.9x10-8

c. formic acid, Ka = 1.86x10-4

d. chloroacetic acid, Ka = 1.26x10-3

e. nitrous acid,  Ka = 4.5x10-4

Solution

We're being asked to identify which of the given acids has the weakest conjugate base.

Recall: The stronger an acid, the weaker its conjugate base, and, conversely, the stronger a base, the weaker its conjugate acid


We need to identify the strongest acid among the given. We can compare their Ka values:

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