6D9

[Lilia Hacoupian 2E]

Why in this problem, when solving for KA, do we subtract the percentage given from 1 in the denominator and then multiply it to 0.11 instead of using subtraction?

[Taylor Aguinaldo 2B]

You can still use (.110 - x) in the denominator like how you originally thought. However, the way the textbook approaches finding the concentration of benzoic acid by doing (1-0.024)(.110), which also works. This is because doing (1-0.024) will give you the percent of how much benzoic acid did not deprotonate. Then, multiplying this by the original concentration to find out how much the concentration is left at equilibrium.