Question

For which type of titration will the ph be acidic at the equivalence point?

a. strong acid vs. strong base.
b. strong acid vs. weak base.
c. weak acid vs. strong base.
d. all of the above.
e. none of the above.

Answer 1

it is
b. strong acid vs. weak base.

Answer 2

Equivalence point in an acid base titration is the point when there are equal moles of acid and base in the solution.

The pH at the equivalence point of a strong acid and a strong base will be 7 as the solution will be neutral. The conjugate acid and the conjugate base of a strong base and strong acid will be neutral.

`HCl(aq) + NaOH(aq)---> NaCl(aq) + H_(2)O(l)`

The pH at the equivalence point of a titration of weak acid and a strong base will be slightly basic as the conjugate base of the weak acid formed in the titration will be basic.

`CH_(3)COOH (aq) + NaOH (aq)--> CH_(3)COONa(aq) + H_(2)O(l)`

The pH at the equivalence point of a titration of strong acid and a weak base will be slightly acidic because the conjugate acid of the weak base is slightly acidic.

`HCl(aq) + NH_(3)(aq) ---> NH_(4)^(+)(aq) + Cl^(-)(aq)`

The pH at the equivalence point of the titration of a weak acid and a weak base is 7. But the pH changes are not sharp as both the acid and base are weak.

`CH_(3)COOH (aq)+NH_(3)(aq) -->CH_(3)COONH_(4)(aq)`

Therefore, the correct answer is B: Strong acid versus weak base