Chapter 10.3, Problem 38PP

Interpretation Introduction

Interpretation:

The mass $4.35\times {10}^{-2}$ mol of zinc chloride ${\text{(ZnCl}}_{\text{2}})$ needs to be determined.

Concept introduction:

The number of moles can be used to calculate mass of a substance using its molar mass. The relation is represented as follows:

$\begin{array}{l}n=\frac{m}{M}\\ Or,\\ m=n\times M\end{array}$

Here, n is number of moles, m is mass and M is molar mass.

Answer to Problem 38PP

The mass of $4.35\times {10}^{-2}$ mol of ${\text{ZnCl}}_{\text{2}}$ is $5.93\text{ g}$.

Explanation of Solution

Given Information:

The number of moles of ${\text{ZnCl}}_{\text{2}}$ is $4.35\times {10}^{-2}$ mol.

Calculation:

To calculate the mass, first calculate molar mass of ${\text{ZnCl}}_{\text{2}}$.

From the above formula, there are 2 Cl atoms and 1 Zn atom in 1 molecule of ${\text{ZnCl}}_{\text{2}}$.

The molar mass of Zn and Cl is 65.38 g/mol and 35.5 g/mol respectively. Therefore, molar mass of ${\text{ZnCl}}_{\text{2}}$ will be:

${\text{M}}_{{\text{ZnCl}}_{\text{2}}}=65.38\text{ g/mol+2}\left(35.45\text{ g/mol}\right)=136.28\text{ g/mol}$

Mass of ${\text{ZnCl}}_{\text{2}}$ can be calculated as follows:

$m=n\times M$

Putting the values,

$\begin{array}{l}m=\left(4.35\times {10}^{-2}\text{ mol}\right)\left(136.28\text{ g/mol}\right)\\ =5.93\text{ g}\end{array}$

Conclusion

Therefore, mass of ${\text{ZnCl}}_{\text{2}}$ is $5.93\text{ g}$.