Chapter 13, Problem 43E

Interpretation Introduction

(a)

Interpretation:

The mass/mass percentage of $\text{1}\text{.25}\text{g}\text{NaCl}$ in $\text{100}\text{.0}\text{g}$ of solution is to be calculated.

Concept introduction:

The percentage composition of a compound is calculated by comparing the mass contributed by each element to the molar mass of the substance. The sum of the percentage composition of each element is equal to the percentage composition of the compound.

Answer to Problem 43E

The mass percentage of $\text{1}\text{.25}\text{g}\text{NaCl}$ in $\text{100}\text{.0}\text{g}$ of solution is $\text{1}\text{.25}\%$.

Explanation of Solution

The mass percentage is calculated by the formula as shown below.

$\text{Mass}\%=\frac{{\text{Mass}}_{\text{NaCl}}}{{\text{Mass}}_{\text{solution}}}\times 100\%$ …(1)

The value of the mass of $\text{NaCl}$ is $\text{1}\text{.25}\text{g}$. The value of the mass of the solution is $\text{100}\text{g}$.

Substitute the value of mass of $\text{NaCl}$ and mass of solution in the equation (1).

$\begin{array}{rll}\text{Mass}\%& =& \frac{{\text{Mass}}_{\text{NaCl}}}{{\text{Mass}}_{\text{solution}}}\times 100\%\\ & =& \frac{\text{1}\text{.25}\text{g}}{\text{100}\text{g}}\times 100\%\\ & =& \text{1}\text{.25}\%\end{array}$

Therefore, the mass percentage of $\text{1}\text{.25}\text{g}\text{NaCl}$ in $\text{100}\text{.0}\text{g}$ of solution is $\text{1}\text{.25}\%$.

Conclusion

The mass percentage of $\text{1}\text{.25}\text{g}\text{NaCl}$ in $\text{100}\text{.0}\text{g}$ of solution is $\text{1}\text{.25}\%$.

Interpretation Introduction

(b)

Interpretation:

The mass percentage of $\text{2}\text{.50}\text{g}{\text{K}}_{\text{2}}{\text{Cr}}_{\text{2}}{\text{O}}_{\text{7}}$ in $\text{95}\text{.0}\text{g}$ of solution is to be calculated.

Concept introduction:

The percentage composition of a compound is calculated by comparing the mass contributed by each element to the molar mass of the substance. The sum of the percentage composition of each element is equal to the percentage composition of the compound.

Answer to Problem 43E

The mass percentage of $\text{2}\text{.50}\text{g}{\text{K}}_{\text{2}}{\text{Cr}}_{\text{2}}{\text{O}}_{\text{7}}$ in $\text{95}\text{.0}\text{g}$ of solution is $\text{2}\text{.63}\%$.

Explanation of Solution

The mass percentage is calculated by the formula as shown below.

$\text{Mass}\%=\frac{{\text{Mass}}_{{\text{K}}_{\text{2}}{\text{Cr}}_{\text{2}}{\text{O}}_{\text{7}}}}{{\text{Mass}}_{\text{solution}}}\times 100\%$ …(1)

The value of mass of ${\text{K}}_{\text{2}}{\text{Cr}}_{\text{2}}{\text{O}}_{\text{7}}$ is $2.50\text{g}$. The value of mass of solution is $\text{95}\text{.0}\text{g}$.

Substitute the value of mass of ${\text{K}}_{\text{2}}{\text{Cr}}_{\text{2}}{\text{O}}_{\text{7}}$ and mass of solution in equation (1).

$\begin{array}{rll}\text{Mass}\%& =& \frac{{\text{Mass}}_{{\text{K}}_{\text{2}}{\text{Cr}}_{\text{2}}{\text{O}}_{\text{7}}}}{{\text{Mass}}_{\text{solution}}}\times 100\%\\ & =& \frac{2.50\text{g}}{95.0\text{g}}\times 100\%\\ & =& \text{2}\text{.63}\%\end{array}$

Therefore, the mass percentage of $\text{2}\text{.50}\text{g}{\text{K}}_{\text{2}}{\text{Cr}}_{\text{2}}{\text{O}}_{\text{7}}$ in $\text{95}\text{.0}\text{g}$ of solution is $\text{2}\text{.63}\%$.

Conclusion

The mass percentage of $\text{2}\text{.50}\text{g}{\text{K}}_{\text{2}}{\text{Cr}}_{\text{2}}{\text{O}}_{\text{7}}$ in $\text{95}\text{.0}\text{g}$ of solution is $\text{2}\text{.63}\%$.

Interpretation Introduction

(c)

Interpretation:

The mass percentage of $\text{10}\text{.0}\text{g}{\text{CaCl}}_2$ in $\text{250}\text{.0}\text{g}$ of solution is to be calculated.

Concept introduction:

The percentage composition of a compound is calculated by comparing the mass contributed by each element to the molar mass of the substance. The sum of the percentage composition of each element is equal to the percentage composition of the compound.

Answer to Problem 43E

The mass percentage of $\text{10}\text{.0}\text{g}{\text{CaCl}}_2$ in $\text{250}\text{.0}\text{g}$ of solution is $\text{4}\text{.0}\%$.

Explanation of Solution

The mass percentage is calculated by the formula as shown below.

$\text{Mass}\%=\frac{{\text{Mass}}_{{\text{CaCl}}_2}}{{\text{Mass}}_{\text{solution}}}\times 100\%$ …(1)

The value of mass of ${\text{CaCl}}_2$ is $\text{10}\text{.0}\text{g}$. The value of mass of solution is $\text{250}\text{g}$.

Substitute the value of mass of ${\text{CaCl}}_2$ and mass of solution in equation (1).

$\begin{array}{rll}\text{Mass}\%& =& \frac{{\text{Mass}}_{{\text{CaCl}}_2}}{{\text{Mass}}_{\text{solution}}}\times 100\%\\ & =& \frac{\text{10}\text{g}}{\text{250}\text{g}}\times 100\%\\ & =& \text{4}\text{.0}\%\end{array}$

Therefore, the mass percentage of $\text{10}\text{.0}\text{g}{\text{CaCl}}_2$ in $\text{250}\text{.0}\text{g}$ of solution is $\text{4}\text{.0}\%$.

Conclusion

The mass percentage of $\text{10}\text{.0}\text{g}{\text{CaCl}}_2$ in $\text{250}\text{.0}\text{g}$ of solution is $\text{4}\text{.0}\%$.

Interpretation Introduction

(d)

Interpretation:

The mass percentage of $\text{65}\text{.0}\text{g}{\text{C}}_{\text{6}}{\text{H}}_{\text{12}}{\text{O}}_{\text{6}}$ in $\text{125}\text{.0}\text{g}$ of solution is to be calculated.

Concept introduction:

The percentage composition of a compound is calculated by comparing the mass contributed by each element to the molar mass of the substance. The sum of the percentage composition of each element is equal to the percentage composition of the compound.

Answer to Problem 43E

The mass percentage of $\text{65}\text{.0}\text{g}{\text{C}}_{\text{6}}{\text{H}}_{\text{12}}{\text{O}}_{\text{6}}$ in $\text{125}\text{.0}\text{g}$ of solution is $\text{52}\text{.0}\%$.

Explanation of Solution

The mass percentage is calculated by the formula as shown below.

$\text{Mass}\%=\frac{{\text{Mass}}_{{\text{C}}_{\text{6}}{\text{H}}_{\text{12}}{\text{O}}_{\text{6}}}}{{\text{Mass}}_{\text{solution}}}\times 100\%$ …(1)

The value of mass of ${\text{C}}_{\text{6}}{\text{H}}_{\text{12}}{\text{O}}_{\text{6}}$ is $\text{65}\text{.0}\text{g}$. The value of mass of solution is $\text{125}\text{g}$.

Substitute the value of mass of ${\text{C}}_{\text{6}}{\text{H}}_{\text{12}}{\text{O}}_{\text{6}}$ and mass of solution in equation (1).

$\begin{array}{rll}\text{Mass}\%& =& \frac{{\text{Mass}}_{{\text{C}}_{\text{6}}{\text{H}}_{\text{12}}{\text{O}}_{\text{6}}}}{{\text{Mass}}_{\text{solution}}}\times 100\%\\ & =& \frac{\text{65}\text{g}}{\text{125}\text{g}}\times 100\%\\ & =& \text{52}\text{.0}\%\end{array}$

The mass percentage of $\text{65}\text{.0}\text{g}{\text{C}}_{\text{6}}{\text{H}}_{\text{12}}{\text{O}}_{\text{6}}$ in $\text{125}\text{.0}\text{g}$ of solution is $\text{52}\text{.0}\%$.

Conclusion

The mass percentage of $\text{65}\text{.0}\text{g}{\text{C}}_{\text{6}}{\text{H}}_{\text{12}}{\text{O}}_{\text{6}}$ in $\text{125}\text{.0}\text{g}$ of solution is $\text{52}\text{.0}\%$.