Chapter 15, Problem 17E

Interpretation Introduction

(a)

Interpretation:

A concept map is to be drawn and the liters of $\text{HF}$ gas dissolved in the solution when $\text{1}\text{.00 g}$ of hydrogen fluoride dissolves in $\text{100 mL}$ of solution is to be calculated.

Concept introduction:

A mole is a basic unit used in the International system of units (SI). It is abbreviated as $\text{mol}$ Mole is defined that the amount of substance that contains molecules or atoms equals to $\text{12}\text{g}$ of $\text{C}-\text{12}$ molecule. The concept map of a mole is a diagram used to relate the different concepts of mole chemistry.

Answer to Problem 17E

The concept map is shown below.

The liters of $\text{HF}$ gas dissolved in the solution when $\text{1}\text{.00 g}$ of hydrogen fluoride dissolves in $\text{100 mL}$ of solution is $\text{1}\text{.12}\text{L}$.

Explanation of Solution

When $\text{1}\text{.00 g}$ of hydrogen fluoride dissolves in $\text{100 mL}$ of solution, mole concept map looks like as shown below.

Figure 1

The formula to calculate the number of moles of $\text{HF}$ gas is given below.

$\text{Number}\text{of}\text{moles}=\frac{\text{Mass}\text{of}\text{HF}}{\text{Molar}\text{mass}\text{of}\text{HF}}$

The mass of $\text{HF}$ gas is $\text{1}\text{.00 g}$.

The molar mass of $\text{HF}$ gas is $20.01\text{g}{\text{mol}}^{-1}$.

Substitute the mass and molar mass of $\text{HF}$ gas in the above equation.

$\begin{array}{rll}\text{Number}\text{of}\text{moles}& =& \frac{\text{1}\text{.00 g}}{\text{20}\text{.01}\text{g}{\text{mol}}^{-1}}\\ & =& \text{0}\text{.05}\text{mol}\end{array}$

The volume occupied by $\text{1}\text{mol}$ of $\text{HF}$ gas at STP is $\text{22}\text{.4}\text{L}$.

The formula to calculate the volume occupied by $\text{0}\text{.05}\text{mol}$ of $\text{HF}$ gas is shown below.

$\text{Volume}= \text{0}\text{.05}\text{mol}\text{HF}\times \frac{\text{Volume}\text{of}\text{1}\text{mol}\text{HF}}{\text{1}\text{mol}\text{HF}}$

Substitute the volume of $\text{1}\text{mol}$ of $\text{HF}$ gas in the above equation.

$\begin{array}{rll}\text{Volume}& =& \text{0}\text{.05}\text{mol}\text{HF}\times \frac{\text{22}\text{.4}\text{L}}{\text{1}\text{mol}\text{HF}}\\ & =& \text{1}\text{.12}\text{L}\end{array}$

Therefore, the liters of $\text{HF}$ gas dissolved in the solution is $\text{1}\text{.12}\text{L}$.

Conclusion

The liters of $\text{HF}$ gas is $\text{1}\text{.12}\text{L}$.

Interpretation Introduction

(b)

Interpretation:

A concept map is to be drawn and the molecules of $\text{HF}$ gas dissolved in the solution in when $\text{1}\text{.00 g}$ of hydrogen fluoride dissolves in $\text{100 mL}$ of solution is to be calculated.

Concept introduction:

A mole is a basic unit used in the International system of units (SI). It is abbreviated as $\text{mol}$ Mole is defined that the amount of substance that contains molecules or atoms equals to $\text{12}\text{g}$ of $\text{C}-\text{12}$ molecule. The concept map of a mole is a diagram used to relate the different concepts of mole chemistry.

Answer to Problem 17E

The concept map is shown below.

The molecules of $\text{HF}$ gas dissolved in the solution in when $\text{1}\text{.00 g}$ of hydrogen fluoride dissolves in $\text{100 mL}$ of solution is $3.01\times {10}^{22}\text{moleules}$.

Explanation of Solution

When $\text{1}\text{.00 g}$ of hydrogen fluoride dissolves in $\text{100 mL}$ of solution, mole concept map looks like as shown below.

Figure 1

The formula to calculate the number of moles of $\text{HF}$ gas is given below.

$\text{Number}\text{of}\text{moles}=\frac{\text{Mass}\text{of}\text{HF}}{\text{Molar}\text{mass}\text{of}\text{HF}}$

The mass of $\text{HF}$ gas is $\text{1}\text{.00 g}$.

The molar mass of $\text{HF}$ gas is $20.01\text{g}{\text{mol}}^{-1}$.

Substitute the mass and molar mass of $\text{HF}$ gas in the above equation.

$\begin{array}{rll}\text{Number}\text{of}\text{moles}& =& \frac{\text{1}\text{.00 g}}{\text{20}\text{.01}\text{g}{\text{mol}}^{-1}}\\ & =& \text{0}\text{.05}\text{mol}\end{array}$

The molecules present in $\text{1}\text{mol}$ of $\text{HF}$ gas at STP are $\text{6}\text{.02}\times {10}^{23}\text{moleules}$.

The formula to calculate the molecules occupied by $\text{0}\text{.05}\text{mol}$ of $\text{HF}$ gas is shown below.

$\text{Number}\text{of}\text{moleucles}= \text{0}\text{.05}\text{mol}\text{HF}\times \frac{\text{Molecules}\text{in}\text{1}\text{mol}\text{HF}}{\text{1}\text{mol}\text{HF}}$

Substitute the molecules in $\text{1}\text{mol}$ of $\text{HF}$ gas in the above equation.

$\begin{array}{rll}\text{Number}\text{of}\text{moleucles}& =& \text{0}\text{.05}\text{mol}\text{HF}\times \frac{\text{6}\text{.02}\times {10}^{23}\text{moleules}}{\text{1}\text{mol}\text{HF}}\\ & =& 3.01\times {10}^{22}\text{moleules}\end{array}$

Therefore, the molecules of $\text{HF}$ gas dissolved in the solution is $3.01\times {10}^{22}\text{moleules}$.

Conclusion

The molecules of $\text{HF}$ gas is $3.01\times {10}^{22}\text{moleules}$.

Interpretation Introduction

(c)

Interpretation:

A concept map is to be drawn and molar concentration of the hydrofluoric solution in the solution in when $\text{1}\text{.00 g}$ of hydrogen fluoride dissolves in $\text{100 mL}$ of solution is to be calculated.

Concept introduction:

A mole is a basic unit used in the International system of units (SI). It is abbreviated as $\text{mol}$ Mole is defined that the amount of substance that contains molecules or atoms equals to $\text{12}\text{g}$ of $\text{C}-\text{12}$ molecule. The concept map of a mole is a diagram used to relate the different concepts of mole chemistry.

Answer to Problem 17E

The concept map is shown below.

The molar concentration of the hydrofluoric acid solution is $0.5M$.

Explanation of Solution

When $\text{1}\text{.00 g}$ of hydrogen fluoride dissolves in $\text{100 mL}$ of solution, mole concept map looks like as shown below.

Figure 1

The formula to calculate the number of moles of $\text{HF}$ gas is given below.

$\text{Number}\text{of}\text{moles}=\frac{\text{Mass}\text{of}\text{HF}}{\text{Molar}\text{mass}\text{of}\text{HF}}$

The mass of $\text{HF}$ gas is $\text{1}\text{.00 g}$.

The molar mass of $\text{HF}$ gas is $20.01\text{g}{\text{mol}}^{-1}$.

Substitute the mass and molar mass of $\text{HF}$ gas in the above equation.

$\begin{array}{rll}\text{Number}\text{of}\text{moles}& =& \frac{\text{1}\text{.00 g}}{\text{20}\text{.01}\text{g}{\text{mol}}^{-1}}\\ & =& \text{0}\text{.05}\text{mol}\end{array}$

The number of moles in $\text{100 mL}$ of solution is $\text{0}\text{.05}\text{mol}$.

The relation between $\text{L}$ and $\text{mL}$ is shown below.

$\text{1}\text{L}=\text{1000}\text{mL}$

The probable unit factors are given below.

$\frac{\text{1}\text{L}}{\text{1000}\text{mL}}\text{and}\frac{\text{1000}\text{mL}}{\text{1}\text{L}}$

The unit factor to determine $\text{L}$ from $\text{mL}$ is given below.

$\frac{\text{1L}}{\text{1000}\text{mL}}$

Therefore, the volume in $\text{L}$ is calculated below.

$\begin{array}{rll}\text{Volume}& =& \text{100 mL}\times \frac{\text{1L}}{\text{1000}\text{mL}}\\ & =& 0.1\text{L}\end{array}$

The formula to determine molarity is shown below.

$M=\frac{\text{n}}{\text{V}}$ …(1)

Where

• $M$ is the molarity of a solution.

• $\text{n}$ is the number of moles of solute.

• $\text{V}$ is the volume of the solution.

Substitute the value of number of moles and volume in equation (1).

$\begin{array}{rll}\text{Molar}\text{concentration}\text{of}\text{HF}& =& \frac{\text{0}\text{.05}\text{mol}}{\text{0}\text{.1 L}}\\ & =& 0.5\text{mol}/\text{L}\end{array}$

The relation between $M$ and $\text{mol}/\text{L}$ as shown below.

$1M=1\text{mol}/\text{L}$

The unit factors are given below.

$\frac{1M}{1\text{mol}/\text{L}}\text{and}\frac{1\text{mol}/\text{L}}{1M}$

The unit factor to determine $M$ from $\text{mol}/\text{L}$ is given below.

$\frac{1M}{1\text{mol}/\text{L}}$

Therefore, $0.5\text{mol}/\text{L}$ can be written as shown below.

$\begin{array}{rll}\text{Molarity}& =& 0.5\text{mol}/\text{L}\times \frac{1M}{1\text{mol}/\text{L}}\\ & =& 0.5M\end{array}$

Therefore, the molar concentration of $\text{HF}$ solution is $0.5M$.

Conclusion

The molar concentration of $\text{HF}$ solution is $0.5M$.