Question

The gas evolved during the reaction of \[CuC{l_2}\] and conc. \[{H_2}S{O_4}\] is
A. neutral
B. basic
C. highly basic
D. acidic

Answer 1

Hint: \[CuC{l_2}\] reacts with conc. \[{H_2}SO\] to give HCl gas which leaves just after the reaction gets completed.

Complete step by step answer:
If we react \[CuC{l_2}\] and conc. \[{H_2}S{O_4}\] , which is concentrated \[{H_2}S{O_4}\] (very dangerous if it gets poured on any body part) at first no reaction will occur. A solution containing copper (I) ions, chloride, hydronium ions, sulfate ions and copper (II) chloride complex will form.But slowly over time, or more quickly if the solution is heated chloride ions will take protons from hydronium ions, forming water and HCl gas (which leaves). This will drive the dissociation of copper (III) chloride complex into the component ions towards completion. Assuming sufficient sulphuric acid \[\left( {{H_2}S{O_4}} \right)\] was added initially, eventually a negligible amount of chloride will remain. At that point if the liquid is boiled off the result will be copper (II) sulfate.
Therefore if we look into its reaction,
\[CuC{l_2} + conc.\,{H_2}S{O_4} \to CuS{O_4} + 2HCl \uparrow \]
The gas formed is HCl which is acidic.

Hence, in this reaction the gas evolved is HCl and it is acidic in nature.

Note:
There are many changes observed in a chemical reaction such as formation of precipitate, colour change, evolution of gas, increase of temperature etc. When metal reacts with acid, hydrogen gas is produced and when metal carbonate reacts with acid, carbon dioxide gas is evolved.