Chapter U1.8, Problem 6E

Interpretation Introduction

Interpretation:

According to copper cycle diagram, when zinc is added to copper sulfate, copper appears back as a solid. The change in the elemental zincis to be explained.

Concept introduction:

In a copper cycle, several chemical reactions take place. 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 6E

When zinc is added to copper sulfate, copper separates out as a solid and zinc dissolves in the solution forming a colorless zinc sulfate solution.

Explanation of Solution

Zinc is a metal which is more reactive than copper. In the copper cycle, zinc is added in the last step of the cycle. Coppersulfate is a blue colored solution formed when sulfuric acid is added to copper oxide. 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. Copperseparates out as dark colored solid which can be obtained by decanting the clear liquid.

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:

${\text{CuSO}}_{\text{4}}\left(aq\right)+\text{ Zn }\left(s\right)\to \text{ Cu }\left(s\right)+{\text{ ZnSO}}_{\text{4}}\left(aq\right)$

Conclusion

This is an example of chemical reaction where a new product is formed as a result of displacement of one metal with another metal. Here, zinc replaces copper in copper sulfate and forms zinc sulfate and copper.