Acids, Bases and Salts — Question 9

(a) Since sodium hydroxide and sulphuric acid both are soluble, an excess of either of them cannot be removed by filtration. Therefore, it is necessary to find out on a small scale, the ratio of the solutions of the two reactants required for complete neutralisation before preparation.

(b) Iron (III) Chloride (FeCl₃) is highly deliquescent. So, to keep it dry fused calcium chloride is used which is a drying agent.

(c) Anhydrous FeCl₃ cannot be prepared by heating the hydrated Iron (III) chloride (FeCl₃.6H₂O) because on heating, FeCl₃.6H₂O produces Fe₂O₃, H₂O, HCl.

2[FeCl₃.6H₂O] $\xrightarrow{\space\Delta\space}$ Fe₂O₃ + 9H₂O + 6HCl