Chapter 9.2, Problem 21PP

Interpretation Introduction

Interpretation:

Whether in the following reaction, single replacement reaction occurs or not needs to be determined and also the balanced equation if the reaction occurs needs to be written.

$\text{K}(s)+{\text{ZnCl}}_{\text{2}}(aq)\to$

Concept introduction:

In a single-replacement reaction, the replacement of atom of an element by the atoms of another element takes place. The replacement is depend upon their reactivity. One example showing this type of reaction is as follows:

$\text{A}\text{+}\text{BX}\to \text{AX}\text{+}\text{B}$

Answer to Problem 21PP

The reaction occurs and the chemical equation for the reaction is,

$\text{2K}(s)+{\text{ZnCl}}_{\text{2}}(aq)\to 2\text{KCl}\left(aq\right)\text{+Zn}\left(s\right)$

Explanation of Solution

To know the replacement of metal by another metal, the activity series of metals must be followed. Activity series of metals contains a list of metals with decreasing chemical reactivity. Highly reactive metal replaces the least reactive metals from a compound.

Potassium is more reactive than zinc according to the activity series of metals. So, K replaces zinc from ${\text{ZnCl}}_{\text{2}}$ and reaction occurs. So, the reaction is,

$\text{2K}(s)+{\text{ZnCl}}_{\text{2}}(aq)\to 2\text{KCl}\left(aq\right)\text{+Zn}\left(s\right)$

Conclusion

Replacement of one metal by another metal can be decided using the activity series of metals.