Question

Acid/base titration experiments could be used to determine all of the following directly except:

• A. the acid concentration of an acidic solution
• B. the alkalinity of a basic solution
• C. the $p{K}_a$ of an unknown weak acid
• D. whether an unknown acid is monoprotic or polyprotic
• E. the molecular weight of an unknown acid or base

Answer 1

Answer: (E)

the molecular weight of an unknown acid or base

By acid/base titration, the acid concentration of acidic solution or alkalinity of a basic solution can be directly determined. The $p{k}_a$ can also be determined as titration will initially lead to a buffer solution, whose $pH$ can be measured.

At the equivalence point, the moles of base is equal to the moles of acid. From this, the molecular weight of unknown acid or base can also be determined.

But whether an acid is monoprotic or polyprotic cannot be directly determined.