Question

In what area of the titration curve for phosphoric acid (h3po4) is the molecule fully deprotonated?

Answer 1

The titration curve should have flat regions centered around each of the

three halfway points (buffer zones) and sharp increases in pH around the

equivalence points.

Initial pH

This is determined by the most acidic of the Ka values and the initial

concentration of the acid. (Same as a monoprotic acid)

Half-way points

At each halfway point, the pH = pKa of the group you are titrating. At this point in

the titration curve, we are in a buffering region, and the curve will be relatively

flat.

Equivalence points

At each equivalence point, the pH is the average of the pKa values above and

below. At the last equivalence point (the endpoint), the pH is determined by the

Kb of the conjugate base of the weakest acid.

Plotting the titration of 100 mL of 0.10 M phosphoric acid with 1.0 M NaOH.

H3PO4 + H2O  H2PO4

-

+ H3O+

Ka1 = 7.5 x 10-3

H2PO4

-

+ H2O  HPO4

2- + H3O+

Ka2 = 6.2 x 10-8

HPO4

2- + H2O  PO4

3- + H3O+

Ka3 = 4.2 x 10-13

Plot these points and connect them to determine the titration curve of phosphoric acid. The curve should be relatively flat around each of the halfway points when we are in a buffering region.

The titration curve should have flat regions centered around each of the

three halfway points (buffer zones) and sharp increases in pH around the

equivalence points.

For more information on the titration curve click on the link below:

brainly.com/question/3130161

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