Question #fa01b

1 Answer
Nov 27, 2016

Answer:

The acid is #"triprotic"#.

Explanation:

#"Moles of NaOH"# #=# #30.5xx10^-3Lxx0.108*mol*L^-1=3.29*mmol.#

#"Moles of acid"# #=# #(0.210*g)/(192*g*mol^-1)=1.10xx10^-3*mol#

So clearly the acid is triprotic.

The only acid I know that fits these properties is citric acid, #C_6H_8O_7#, which is one of the few triacids. I have never titrated this one, but I think you would be hard-pressed to get a phenolpthalein endpoint at the third equivalent.