Ka for acetic acid, ch3cooh, is 1.80×10-5.ka for acetylsalicylic acid (aspirin), hc9h7o4, is 3.00×10-4.ka for benzoic acid, c6h5cooh, is 6.30×10-5.what is the formula for the weakest conjugate base?

The weakest conjugate base is C9H7O4⁻ which is the conjugate base of Aspirin.

Explanation:

The higher the Ka, the stronger the acid thus the weaker its conjugate base.

Ka of the acid are provided:

CH3COOH = 1.80*10-5

HC9H7O4 = 3.00*10-4

C6H5COOH = 6.30*10-5

From the Ka above, HC9H7O4 have the highest therefore its conjugate acid is the weakest.

When it donates the proton, it becomes the conjugate base.

HC9H7O4 + H2O ⇄ C9H7O4⁻ + H3O⁺