2.5 Ka and the pH of Weak Acids Flashcards
1
Q
what is HA equal to
A
c
the original acid concentration
2
Q
pH equation for strong acids
A
pH = -log [H+]
3
Q
pH = -log [H+]
A
equation for strong acids
4
Q
what is pKa equal to
A
-log Ka
5
Q
pH equation for weak acids
A
pH = 1/2 pKa - 1/2 logC
6
Q
pH = 1/2 pKa - 1/2 logC
A
equation for weak acids
7
Q
what to do if acid is named in a pH question
A
look up in the data booklet as pKa is given
8
Q
what is the pH of a 0.1 mol l-1 solution of a weak acid where the Ka is 4 x 10-5?
A
pH = 1/2 pKa - 1/2 log C
pH = -log Ka / 2 - logC/ 2
pH = -log4 x 10-5 / 2 - log 0.1 / 2
pH = 2.69
9
Q
what is the pH of a 0.35 mol l-1 solution of boric acid?
A
data booklet: pKa is 9.27
pH = 1/2 pKa - 1/2 log C
pH = 1/2 9.27 - 1/2 log 0.35
pH = 4.86
