Question

Anhydrous $FeC{l_2}$ is made by:
A.Heating $Fe$ with dilute $HCl$
B.Heating $Fe$ with gaseous $HCl$
C.Reacting $Fe$ with conc. $HCl$
D.Heating $Fe$ with $C{l_2}$ gas

Answer 1

Hint:If a substance is termed as anhydrous, it signifies that it does not have water. We get anhydrous compounds from crystalline compounds when the water of crystallization is removed.

Complete step by step answer:
When iron is heated with dilute hydrochloric acid, we obtain ferrous chloride which due to the presence of water in the solution is hydrated.
When we heat iron with gaseous hydrogen chloride, anhydrous ferrous chloride is formed
When iron is heated with concentrated hydrochloric acid, we obtain ferrous chloride which due to the presence of water in the solution is hydrated.
When iron is heated in the presence of chlorine gas, the product obtained is ferric chloride. The oxidation state of iron is three rather than two.

Thus, the correct answer is B.

Note:
Anhydrous ferrous chloride is a white colored sample. It crystallizes with four molecules of water forming a green colored crystalline salt which is ferrous chloride anhydrous. It is paramagnetic in nature and the solid has a high magnetic point. It is soluble in water.
It is commonly used as a flocculating or coagulating agent in the treatment of waste water, in order to remove wastes that contain chromates and sulfides. It is also preferred in waste water treatment for odor control. Ferrous chloride is used as a precursor to make various grades of hematite which can further be used in the formation of a variety of pigments. It is also used to prepare hydrated iron (III) oxide, which are magnetic pigments. It is also used as a reagent in synthesis of many organic compounds.