Question

Consider a titration performed using actic acid and aqueous ammonia. which of the following statements is correct?

a. the solution is buffered before and after the equvalence point
b. the equvalence point would be at ph>10
c. methyl orange (ph color range 3.1-4.4) could be a suitable indicator
d. there is a rapid chang ein ph throughout the entire titration
e. an acidic salt is present at the equvalence point

Answer 1

The correct statement for a titration using acetic acid and aqueous ammonia is that the equivalence point will be at a pH > 7, and an indicator like phenolphthalein with a pKin > 7.0 should be used. A buffer solution exists before the equivalence point, and the resultant salt is basic.

Step-by-step explanation:

Considering a titration performed using acetic acid and aqueous ammonia, the correct statement is that the equivalence point would be at pH > 7. This is due to acetic acid being a weak acid and ammonia being a weak base; thus, at the equivalence point, we typically find the pH to be greater than 7. Furthermore, an indicator like phenolphthalein, with pKin > 7.0, would be suitable for such a titration as it changes color at a pH that closely matches the rapid change in pH at the equivalence point for a weak acid titration. Methyl orange would not be as suitable because its color change range is between pH 3.1 - 4.4, which does not correspond well to the pH change at the equivalence point of this titration. There will be a buffer solution present before the equivalence point due to the presence of acetate ions from the partially neutralized acetic acid and ammonium ions from the partially neutralized ammonia. Lastly, the product at the equivalence point is an ammonium acetate solution, which will be basic rather than acidic because of the weak acid and weak base properties.