Chapter 10.3, Problem 29PP

Interpretation Introduction

Interpretation: The number of moles of ${\mathrm{Cl}}_{}^{-}$ ions in 2.50 mol of ${\text{ZnCl}}_{\text{2}}$ need to be determined.

Concept introduction: The number of moles of a particular atom in a molecule can be calculated from its molecular formula. The subscript used for atoms in the molecular formula is equal to the number of moles of atom present in 1 mol of the molecule or compound.

Answer to Problem 29PP

5moles of ${\mathrm{Cl}}_{}^{-}$ ions

Explanation of Solution

Given: The number of moles of ${\text{ZnCl}}_{\text{2}}$ is 2.50 mol.

Calculation: If the molecular formula of a compound is $A_x{B}_y$ , 1 mol of compound contains x mol of A and y mol of B.

Now, the molecular formula of the given compound is ${\text{ZnCl}}_{\text{2}}$ thus, there are 1 mol of Zn and 2 moles of Cl in 1 mol of ${\text{ZnCl}}_{\text{2}}$ .

Thus, the number of moles of ${\mathrm{Cl}}_{}^{-}$ ions in 2.50 mol of ${\text{ZnCl}}_{\text{2}}$ will be:

$\begin{array}{l}{n}_{{\text{Cl}}^{-}}=2\times 2.50\text{ mol}\end{array}$

  $\begin{array}{c}=5.0\text{ mol}\end{array}$

Conclusion

Thus, the number of moles of ${\mathrm{Cl}}_{}^{-}$ ions is 5.0 mol.