Chapter U4.78, Problem 4E

Interpretation Introduction

Interpretation : The moles of the molecules are to be stated in the increasing order.

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 4E

The compounds in increasing order of moles are as follows.

${\text{C}}_8{\text{H}}_{18}<{\text{CH}}_{\text{4}}\text{O}<{\text{H}}_{\text{2}}\text{O}$

Explanation of Solution

Given information : The given mass of ${\text{CH}}_{\text{4}}\text{O}$ , ${\text{H}}_{\text{2}}\text{O}$ , and ${\text{C}}_{\text{8}}{\text{H}}_{\text{18}}$ are $\text{2}\text{.0}\text{g}$ .

The molar mass of ${\text{CH}}_{\text{4}}\text{O}$ is

$\text{33}\text{.035}\text{g}$ . Substitute the given mass as $\text{2}\text{.0}\text{g}$ and molar mass as $\text{33}\text{.035}\text{g}$ for ${\text{CH}}_{\text{4}}\text{O}$ in equation (1) as shown below.

  $\begin{array}{c}\text{Number of moles}=\frac{2.0\text{g}}{\text{33}\text{.035}\frac{\text{g}}{\text{mol}}}\\ =0.060\text{mol}\end{array}$

The molar mass of ${\text{H}}_{\text{2}}\text{O}$ is $\text{18}\text{.015}\text{g}$ . Substitute the given mass as $\text{2}\text{.0}\text{g}$ and molar mass as $\text{18}\text{.015}\text{g}$ for ${\text{H}}_{\text{2}}\text{O}$ in equation (1) as shown below.

  $\begin{array}{c}\text{Number of moles}=\frac{2.0\text{g}}{\text{18}\text{.015}\frac{\text{g}}{\text{mol}}}\\ =0.111\text{mol}\end{array}$

The molar mass of ${\text{C}}_{\text{8}}{\text{H}}_{\text{18}}$ is $114.23\text{g}$ . Substitute the given mass as $\text{2}\text{.0}\text{g}$ and molar mass as $114.23\text{g}$ for ${\text{C}}_{\text{8}}{\text{H}}_{\text{18}}$ in equation (1) as shown below.

  $\begin{array}{c}\text{Number of moles}=\frac{2.0\text{g}}{114.23\frac{\text{g}}{\text{mol}}}\\ =0.0175\text{mol}\end{array}$

Therefore, the compounds in increasing order of moles are as follows.

${\text{C}}_8{\text{H}}_{18}<{\text{CH}}_{\text{4}}\text{O}<{\text{H}}_{\text{2}}\text{O}$

Conclusion

The compounds in increasing order of moles are as follows.

${\text{C}}_8{\text{H}}_{18}<{\text{CH}}_{\text{4}}\text{O}<{\text{H}}_{\text{2}}\text{O}$