In this experiment, i have to titrate a known concentration of the weak acid potassium hydrogen phthalate (KHP) with a strong base, NaOH. From the titration curve, which is a plot of the pH veruss the volume of the NaOH added (which is the X axis), I need to determin the acid ionization constant (Ka) for KHP.

The weak acid KHP is a salt that dissociates in water

KHC8H4O4 (s)--> K+ (aq) + HC8H4O4- (aq)

It is an anion (HC8H4O4) that behaves like an acid:

HC8H4O4- + H2o <--> H3o+ + C8H4O4 Ka for KHP= [H3o][C8H4O4]/[HC8H4O4]

When titrated with NaOH (strong base), the NaOH will react with the acid:

NaOH + HC8H4O4 --> H20 + NaC8H4O4

We have 0.1 M of NaOH, and we use 20 ml of NaOH to get to the equivalence point. We use 0.4 g KHP.

In this experiment, i have to titrate a known con

a). from the titration cuve (NaOH added on x axis, recorded pH on the Y axis), determine the equivalence point and helfway point

b). from the halfway point, determine the Ka for KHP

c). from the equivalence point, determine the exact concentration of NaOH

d). Using the Ka and the known concentration of KHP, calculate the initial pH of the acid and compare to the experimental value