Chapter U4.78, Problem 5E

Interpretation Introduction

Interpretation : The mass of $\text{BaO}$ and ${\text{BaO}}_{\text{2}}$ is given. The molecule with greater number of oxygen atoms has to be predicted.

Concept Introduction : The formula to calculate the number of moles is given as shown below.

  $\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ (1)

Answer to Problem 5E

The more number of mole of oxygen atoms is present in given mass of ${\text{BaO}}_{\text{2}}$ .

Explanation of Solution

Given information : The given mass of $\text{BaO}$ is $\text{153}\text{g}$ and given mass of ${\text{BaO}}_{\text{2}}$ is $\text{169}\text{g}$ .

The molar mass of $\text{BaO}$ is $\text{153}\text{.33}\text{g}$ . Substitute the given mass as $\text{153}\text{g}$ and molar mass as $\text{153}\text{.33}\text{g}$ for $\text{BaO}$ in equation (1) as shown below.

  $\begin{array}{c}\text{Number of moles}=\frac{153\text{g}}{\text{153}\text{.33}\frac{\text{g}}{\text{mol}}}\\ =1\text{mol}\end{array}$

The molar mass of ${\text{BaO}}_{\text{2}}$ is $\text{169}\text{.33}\text{g}$ . Substitute the given mass as $\text{169}\text{g}$ and molar mass as $\text{169}\text{.33}\text{g}$ for ${\text{BaO}}_{\text{2}}$ in equation (1) as shown below.

  $\begin{array}{c}\text{Number of moles}=\frac{169\text{g}}{\text{169}\text{.33}\frac{\text{g}}{\text{mol}}}\\ =1\text{mol}\end{array}$

It is seen that in $\text{153}\text{g}$ of $\text{BaO}$ there is $1\text{}\text{mol}$

$\text{BaO}$ molecules. One molecule of $\text{BaO}$ consists of one atom of oxygen. Therefore, one mole of oxygen atoms are present in one mole of $\text{BaO}$ .On the other hand, in $\text{169}\text{g}$ of ${\text{BaO}}_{\text{2}}$ there is $1\text{}\text{mol}$

${\text{BaO}}_{\text{2}}$ molecules. One molecule of ${\text{BaO}}_{\text{2}}$ consists of two atoms of oxygen. Therefore, two mole of oxygen atoms are present in one mole of ${\text{BaO}}_{\text{2}}$ . Thus, later has more number of oxygen atoms.

Conclusion

The more number of mole of oxygen atoms is present in given mass of ${\text{BaO}}_{\text{2}}$ .