Chapter 6, Problem 26A

(a)

Interpretation Introduction

Interpretation:

The number of moles of carbon atoms present in ethanol is to be calculated.

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 26A

The number of carbon atoms present in ethanol is $\text{0}\text{.055}\text{mol}$ .

Explanation of Solution

The molar mass of ${\text{C}}_2{\text{H}}_5\text{OH}$ is $\text{46}\text{.07}\text{g}/\text{mol}$ . Substitute the given mass as $\text{1}\text{.271}\text{g}$ and molar mass as $\text{46}\text{.07}\text{g}/\text{mol}$ for ${\text{C}}_2{\text{H}}_5\text{OH}$ in equation (1) as shown below:

  $\begin{array}{c}\text{Number of moles}=\frac{1.271\text{g}}{46.07\frac{\text{g}}{\text{mol}}}\\ =0.0275\text{mol}\end{array}$

The chemical formula of ethanol shows that two moles of carbon atoms are present in one mole of ethanol. Therefore, the number of carbon atoms present in ethanol is,

  $\begin{array}{l}=2\times 0.0275\text{mol}\\ =\text{0}\text{.055}\text{mol}\end{array}$

(b)

Interpretation Introduction

Interpretation:

The number of moles of carbon atoms present in 1,4-dichlorobenzene is to be calculated.

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 26A

The number of carbon atoms present in 1,4-dichlorobenzene is $\text{0}\text{.162}\text{mol}$ .

Explanation of Solution

The molar mass of ${\text{C}}_6{\text{H}}_4{\text{Cl}}_2$ is $\text{147}\text{.00}\text{g}/\text{mol}$ . Substitute the given mass as $\text{3}\text{.982}\text{g}$ and molar mass as $\text{147}\text{.00}\text{g}/\text{mol}$ for ${\text{C}}_6{\text{H}}_4{\text{Cl}}_2$ in equation (1) as shown below:

  $\begin{array}{c}\text{Number of moles}=\frac{3.982\text{g}}{\text{147}\text{.00}\frac{\text{g}}{\text{mol}}}\\ =0.0270\text{mol}\end{array}$

The chemical formula of 1,4-dichlorobenzene shows that six moles of carbon atoms are present in one mole of 1,4-dichlorobenzene. Therefore, the number of carbon atoms present in 1,4-dichlorobenzene is,

  $\begin{array}{l}=6\times 0.0270\text{mol}\\ =\text{0}\text{.162}\text{mol}\end{array}$

(c)

Interpretation Introduction

Interpretation:

The number of moles of carbon atoms present in carbon suboxide is to be calculated.

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 26A

The number of carbon atoms present in carbon suboxide is $\text{0}\text{.0195}\text{mol}$ .

Explanation of Solution

The molar mass of ${\text{C}}_3{\text{O}}_2$ is $\text{68}\text{.03}\text{g}/\text{mol}$ . Substitute the given mass as $0.4438\text{g}$ and molar mass as $\text{68}\text{.03}\text{g}/\text{mol}$ for ${\text{C}}_3{\text{O}}_2$ in equation (1) as shown below:

  $\begin{array}{c}\text{Number of moles}=\frac{0.4438\text{g}}{68.03\frac{\text{g}}{\text{mol}}}\\ =0.0065\text{mol}\end{array}$

The chemical formula of carbon suboxide shows that three moles of carbon atoms are present in one mole of carbon suboxide. Therefore, the number of carbon atoms present in carbon suboxide is,

  $\begin{array}{l}=3\times 0.0065\text{mol}\\ =\text{0}\text{.0195}\text{mol}\end{array}$

(d)

Interpretation Introduction

Interpretation:

The number of moles of carbon atoms present in methylene chloride is to be calculated.

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 26A

The number of carbon atoms present in methylene chloride is $\text{0}\text{.0342}\text{mol}$ .

Explanation of Solution

The molar mass of ${\text{CH}}_2{\text{Cl}}_2$ is $\text{84}\text{.93}\text{g}/\text{mol}$ . Substitute the given mass as $2.910\text{g}$ and molar mass as $\text{84}\text{.93}\text{g}/\text{mol}$ for ${\text{CH}}_2{\text{Cl}}_2$ in equation (1) as shown below:

  $\begin{array}{c}\text{Number of moles}=\frac{2.910\text{g}}{\text{84}\text{.93}\frac{\text{g}}{\text{mol}}}\\ =0.0342\text{mol}\end{array}$

The chemical formula of methylene chloride shows that one mole of carbon atoms is present in one mole of methylene chloride. Therefore, the number of carbon atoms present in methylene chloride is,

  $\begin{array}{l}=1\times 0.0342\text{mol}\\ =\text{0}\text{.0342}\text{mol}\end{array}$