- #1

Euler2718

- 90

- 3

## Homework Statement

What is the likely identity of a weak acid if a 0.50 mol/L solution of the acid has a pH of 3.18?

## Homework Equations

HA + H2O <=> H3O + A

[tex] K_{a} = \frac{[P]}{[R]} [/tex]

[tex] [H3O] = 10^{-pH} [/tex]

## The Attempt at a Solution

[/B]

I set up an ICE table with the concentration given, then solved for x using the inverse log formula for [H3O], finally I did the following Ka expression:

[tex] K_{a} = \frac{(6.6 \times 10^{-4})^{2}}{0.5-6.6 \times 10^{-4}} = 8.75 \times 10^{-7} [/tex]

The closets acid to that appears to be carbonic acid (ka = 4.4x10^-7). Any suggestions?