Question

An aqueous solution of orthoboric acid can be titrated against sodium hydroxide using phenolphthalein indicator only in presence of:

• A. trans-glycerol
• B. catechol
• C. cis-glycerol
• D. both (B) and (C)

Answer 1

Answer: (D)

both (B) and (C)

It forms a stable cyclic complex with polyhydroxy compounds like cis-glycerol, catechol, etc. This helps in the release of $H^{+}$ and $H_3{O}^{+}$ and, therefore, boric acid acts as a strong acid and hence can be titrated with sodium hydroxide using phenolphthalein.