Question

1st attempt Feedback ♡ See Hint The leaves of the rhubarb plant contain high concentrations of diprotic oxalic acid (HOOCCOOH) and must be removed before the stems are used to make rhubarb pie. If pKa1 = 1.23 and pKa2 = 4.19, what is the pH of a 0.0255 M solution of oxalic acid? * 1.66

Answer 1

The first step reaction is as follows: Reqction: HOOCCOOH an HOOCCOOH — H+ + HOOCCOO- Initial: 0.0255 0 0 Change: + x + x Equilibrium: 0.0255 - x + x + x Ka = 10-1.23 - _ xxx 0.0255 - x x = 0.019224 M OOCC002- The second step reaction is as follows: Reqction: HOOCC00 - € H* + Initial: 0.019224 0.019224 Change: - x +x Equilibrium: 0.019224 - x 0.019224 + x +x + x Kg = 10-4-19 (0.019224+x)xx 0.019224 - x x = 0.000064136 M Calculate the pH as follows: pH = -log( 0.019224 +0.000064136) pH = 1.71471 Therefore, answer is 1.71. Please give good rating.