Key Reagents for Tests

Question 1

Barium Chloride

Answer 1

Uses acidified barium chloride to test for sulfate ions in solution.

Question 2

Benedict’s Solution

Answer 2

Deep blue Cu²⁺ complex, which reduces to a brick-red Cu₂O precipitate when warmed with an aldehyde, but stays blue with a ketone.

Question 3

Fehling’s Solution

Answer 3

A deep blue Cu²⁺ complex, which reduces to a brick-red Cu₂O precipitate when warmed with an aldehyde, but stays blue with a ketone.

Question 4

Silver Nitrate

Answer 4

Uses silver nitrate to identify halide ions in solution

Question 5

Tollens’ Reagent

Answer 5

[Ag(NH₃)₂]⁺. It is reduced to silver when warmed with an aldehyde, but not with a ketone. (Silver mirror precipitate with aldehyde).