Question

The deliquescent salt P turns yellow on dissolving in water and gives a reddish-brown precipitate with sodium hydroxide solution. Substance P is Ferric Chloride $FeC{l_3}$.
a. True
b. False

Answer 1

Hint- we must know that ferric chloride is insoluble salt in nature. It ranges in colour from dark-brown to black.

Complete step by step answer:
We must remember that the ferric chloride $FeC{l_3}$ is an inorganic salt where iron has an oxidation state of+3. The anhydrous iron (III) chloride has a relatively low melting point. Hence, the salt $FeC{l_3}$ is deliquescent in nature. It forms hydrated hydrogen chloride mists when reacting with moist air.
FeCl3 is completely soluble in water. If we dissolve it in water it results in the dissociation of ions present in the salt. So we must understand the salt in its aqueous solution dissociates into Fe3+ and Cl- ions.
\[FeC{l_3} \to F{e^{3 + }} + C{l^ - }\]
Therefore, we can see that colour Fe3+ ions range from a yellow to light brown in color. This is the reason why $FeC{l_3}$ turns yellow on dissolving in water. The balanced chemical equation for this reaction is:
\[FeC{l_3} + {H_2}O \to Fe{(OH)_3} + HCl\]
When we see the reaction of the iron (III) chloride with aqueous sodium hydroxide solution, it results in the production of a reddish-brown precipitate which is ferric hydroxide. The chemical equation for this reaction is given below:
\[3NaOH + FeC{l_3} \to Fe{(OH)_3} \downarrow + 3NaCl\]
              We can understand the ferric hydroxide gets precipitated here because Fe (OH)3 is insoluble in sodium hydroxide (NaOH).

As all the three conditions are satisfied, the substance P is ferric chloride $FeC{l_3}$ . Hence the answer is option (a) which is True.

Note: We must understand the colour of the anhydrous $FeC{l_3}$ depends on the viewing angle. When we viie it with reflected light, the crystals are dark green. But when we view it with transmitted light, the crystals appear purple to red.