A buffer solution has a pH of 4.69 and contains 0.15 mol of propanoic acid and 0.10 mol of sodium propanoate. Use these data to calculate a value of Ka for propanoic acid.
[H+] = pH^4.69 = 2.04x10^-5
I get that.
I know you have to use Ka= [H+][CH3CH2COO-] / [CH3CH2COOH]
But how the heck do i know the conc. of [CH3CH2COO-] and [CH3CH2COOH], they have only given the number of moles
They do Ka =(2.04 × 10)(0.10) / (0.15)
but 0.10 and 0.15 are the moles and conc at all?
Buffer question Watch
- Thread Starter
- 05-12-2010 19:17
- 05-12-2010 20:53
It's because the volumes cancel in the equation, so only the moles are neededLast edited by EierVonSatan; 05-12-2010 at 20:55.
- 06-12-2010 16:04
It will have probally meant Mol/dm^-3