Question

The group reagent for the test of alcohol is:
A. Ceric ammonium nitrate
B. Schiff’s reagent
C. Molisch’s reagent
D. Bromine water

Answer 1

Hint: It is an inorganic compound with orange red color and dissolving gives a yellow color solution. It is used as a one-electron oxidizing agent which is used in the oxidative addition reaction of alkenes. On reacting with secondary alcohol it forms ketone.

Complete step by step answer:
A.Ceric ammonium nitrate $({(N{H_4})_2}Ce{(N{O_3})_6})$ is used to test the alcoholic group. On reacting with compound carrying alcohol groups it gives the red color solution. This red color indicates the presence of alcohol.
The reaction of ceric ammonium nitrate with alcohol is shown below.
$2R - OH + {(N{H_4})_2}Ce{(N{O_3})_6} \to R{(OH)_2}Ce{(N{O_3})_4} + 2N{H_4}N{O_3}$
$R{(OH)_2}Ce{(N{O_3})_4}$shows red color.
B.Schiff’s reagent is used for testing of the aldehydic group. When Schiff’s reagent is reacted with a compound carrying aldehydic group it gives a red or pink color solution. This red color indicates the presence of an aldehydic group.
The reaction of Schiff’s reagent with alcohol is shown below.
$RCHO\xrightarrow{{Schiff'sreagent}}redsolution$
C.Molisch’s reagent is used for testing carbohydrate groups. Molisch’s reagent on reacting with carbohydrate group in presence of sulfuric acid gives violet ring which detects the presence of carbohydrate.
D. Bromine water is used for detecting unsaturated compounds having a double or triple bonds. The unsaturated compound reacting with bromine water decolorizes the solution. This detects the presence of a double or triple bond.
Thus, the group reagent used to detect alcohol is cerium ammonium nitrate.

Thus, the correct option is option (A).

Note:
During the reaction between the cerium ammonium nitrate and alcohol group, the change in the group in the cerium ion changes the electronic structure which results in a change of color. The two ammonium cations in the reagent act as a spectator ion but do not participate in the reaction.