Question
I took 25 mL of an unknown weak acid and added it to 10 mL of NaOH solution. I measured the pH and got 2.88 with concentration of NaOH @ .0098 and weak acid at 0.0102. What is pKa for the acid?
Answers
DrBob222
pH = pKa + log (base)/(acid)
Set up an ICE chart and use the above equation.
25.0 x 0.0102 = 0.255 mols
10 x 0.0098 0.098 mols
.........HA + OH^- ==> H2O + A^-
I......0.255.....0........0.....0
added.........0.098...........
C....-0.098.-0.098......0.098
E ....0.157...0..........0.098...
Post your work if you get stuck.
Set up an ICE chart and use the above equation.
25.0 x 0.0102 = 0.255 mols
10 x 0.0098 0.098 mols
.........HA + OH^- ==> H2O + A^-
I......0.255.....0........0.....0
added.........0.098...........
C....-0.098.-0.098......0.098
E ....0.157...0..........0.098...
Post your work if you get stuck.