Question

URGENT!
In the titration of a weak acid HA with 0.100 M NaOH, the stoichiometric point is known to occur at a pH value of approximately 11. Which of the following indicators would be best to use to mark the endpoint of this titration?
A) an indicator with Ka = 10^–10
B) an indicator with Ka = 10^–8
C) an indicator with Ka = 10^–14
D) an indicator with Ka = 10^–11
E) an indicator with Ka = 10^–12
I know the answer..I don't get how??

Answer 1

(E) An indicator with Ka = 10-

Answer 2

LOL

Its..... D) an indicator with Ka = 10^–11

An indicator will change color when the pH bypasses its pka......and you know its the end point of a titration.

Answer 3

Hmmm...