Chapter U1.7, Problem 3E

Interpretation Introduction

Interpretation:

According to copper cycle diagram, when zinc is added to blue colored solution, it turned colorless and copper appeared back as a solid. The reason for this observationis to be explained.

Concept introduction:

In a copper cycle, several chemical reactions are done. The cycle starts with copper and ends with copper. Copper is made to react with acids, abase and a metal at different stages. Several intermediate products are formed and a gas is also produced. The cycle involves five different steps and in each step, a new substance is formed.

Answer to Problem 3E

When zinc is added to blue colored solution, the solution turns colorless due to the formation of zinc sulfate solution which is colorless. Copperseparates out as a solid.

Explanation of Solution

Given information:

In a copper cycle, zinc is added to blue colored solution and the solution turns colorless. Copper separates out as a solid.

Zinc is a metal which is more reactive than copper. In the copper cycle zinc is added in the last step of the cycle. The blue colored solution is of copper sulfate. When zinc is added to copper sulfate solution, the copper ions get replaced by zinc and zinc sulfate is formed. Zinc sulfate solution is colorless. The copper ions separate out as dark colored solid.

This kind of reaction is called displacement reaction where a metal displaces another less reactive metal from its salt solution.

The chemical reaction can be represented as below:

CuSO₄ (aq) + Zn (s) → Cu (s) + ZnSO₄ (aq)

Conclusion

This is an example of chemical reaction where a new product is formed as a result of reaction between zinc and copper sulfate. The change in color, from blue to colorless indicates that a chemical reaction has occurred. New products formed are zinc sulfate and copper.