12.2.3 - Finding ka from titration curves Flashcards
1
Q
What type of titration curve can be used to calculate Ka?
A
A weak acid titrated with a strong base
2
Q
What is the buffer region on a titration curve?
A
The horizontally flat part of the curve before the equivalence point.
Addition of base has no real change to pH
3
Q
How to we find Ka using a titration curve?
A
Find equivalence point (volume)
Half the value, the pH at this value is the PKa.
Ka = 10^-PKa
4
Q
How do you experimentally determine Ka from a titration?
A
Do a titration between the weak acid and strong base with the base in the burette and acid in the flask.
Add a phenolphthalein.
Determine equivalence point - e.g 30cm^3
Repeat the titration again and only add half of the base (15cm^3)
No phenolphthalein needs to be added.
Measure PH
work out ka using 10^-PKa
