................H3BO3.....................H^+...........H2BO3^-
I..............0.001..........................0................0
C................-x.............................x..................x
E.............0.001-x........................x..................x
Ka = (H^+)(H2BO3^-)/(H3BO3)
Substitute and solve for x = (H^+) and convert to pH
For the titration, the pH at the equivalence point is 7.0 or very close to that. Alizarin yellow is 10 and above, methyl violet is very low. would use methyl red. It's average is about 5 the the pH titration curve is so steep at that point in the titration that the error will be minimal.
1. What is the pH of a 1.0 x 10-3 M solution of boric acid, H3BO3? The Ka value for boric acid is 6 x 10-10.
(choices: 3, 7, between 7 and 12, between 3 and 7)
2. You want to use a 0.500 M HNO3 solution to titrate an unknown concentration of KOH solution. Which indicator would be the best for this titration?
(choices: Methyl violet, Methyl red, Alizarin yellow)
1 answer
1 answer