Chapter U1, Problem 16STP

Interpretation Introduction

Interpretation:

The solid substance produced in the copper cycle needs to be identified.

Concept introduction:

All matter can exist in three possible states; solid, liquid and gases. These states are different from each other in their arrangement of constituent particles and also their intermolecular forces.

Solid states have strongest intermolecular force of attraction between molecules whereas gaseous state has weakest force of attraction.

Answer to Problem 16STP

Option (D) is correct option.

Explanation of Solution

Reason for correct option: Copper cycle is a series of conversion of solid to copper to again back to solid copper after different chemical changes. Reaction with HNO₃ forms copper nitrate which further changes to copper oxide. Reaction of copper oxide with sulfuric acid forms copper sulfate which further reacts with Zn to form copper metal and zinc sulfate. The reactions can be summarized as:

$\begin{array}{l}{\text{Cu}}_{\text{(s)}}{\text{+ 4HNO}}_{\text{3(aq)}}\stackrel{}{\to }{\text{Cu(NO}}_{\text{3}}{\text{)}}_{\text{2(aq)}}{\text{+ 2 NO}}_{\text{2(g)}}{\text{+ 2H}}_{\text{2}}{\text{O}}_{\text{(l)}}\\ {\text{Cu(NO}}_{\text{3}}{\text{)}}_{\text{2(aq)}}\text{+ 2 NaOH(aq)}\stackrel{}{\to }{\text{ Cu(OH)}}_{\text{2(aq)}}{\text{+ 2 NaNO}}_{\text{3}}{}_{\text{(aq)}}\\ {\text{Cu(OH)}}_{\text{2(aq)}}\stackrel{}{\to }{\text{CuO}}_{\text{(s)}}{\text{+H}}_{\text{2}}{\text{O}}_{\text{(l)}}\\ {\text{CuO}}_{\text{(s)}}{\text{+ H}}_{\text{2}}{\text{SO}}_{\text{4(aq)}}\stackrel{}{\to }{\text{CuSO}}_{\text{4(aq)}}{\text{+H}}_{\text{2}}{\text{O}}_{\text{(l)}}\end{array}$

According to all chemical reactions, CuO exists in solid state.

Conclusion

Reasons for incorrect options:

• Nitrogen dioxide = gaseous state
• Sulfuric acid = aqueous state
• Copper hydroxide = aqueous state