This question is about weak acids.
Benzoic acid, C6H5COOH\text{C}_6\text{H}_5\text{COOH}C6H5COOH, is a weak monobasic acid.
Write the expression for the acid dissociation constant, KaK_aKa, of C6H5COOH\text{C}_6\text{H}_5\text{COOH}C6H5COOH.
The expression for the acid dissociation constant, KaK_aKa, of C6H5COOH\text{C}_6\text{H}_5\text{COOH}C6H5COOH can be simplified to:
Ka=[H+]2[C6H5COOH]K_a = \frac{[\text{H}^+]^2}{[\text{C}_6\text{H}_5\text{COOH}]}Ka=[C6H5COOH][H+]2
State one approximation that allows the original expression to be simplified to this form.
An analyst performs a titration preparation and measures the pKa\text{p}K_apKa of a sample of C6H5COOH\text{C}_6\text{H}_5\text{COOH}C6H5COOH at 298 K298\text{ K}298 K.
Use the simplified expression to calculate the pKa\text{p}K_apKa value of C6H5COOH\text{C}_6\text{H}_5\text{COOH}C6H5COOH. Give your answer to 2 decimal places.