Chapter 15, Problem 29A

(a)

Interpretation Introduction

Interpretation:

The number of moles in 10.2 mL of 0.451 M AlCl₃ solution needs to be determined.

Concept Introduction:

The molarity is the number of moles of the solute dissolved per liter volume of the solution. It is represented in mathematical term such that,

  $\begin{array}{l}M=\text{molarity=}\frac{\text{number}\text{of}\text{moles}\text{of}\text{solute}}{\text{volume}\text{of}\text{the}\text{solution}}\\ M=\frac{n}{V\left(\text{L}\right)}\end{array}$

Where, n is the number of moles,

L is the volume of the solution.

Answer to Problem 29A

  $4.6\times {10}^{-3}\text{mol}$

Explanation of Solution

Given information:

The volume is, $V=10.\text{2 mL}=10.2\times {10}^{-3}\text{L}$

The molarity is, $M=0.4\text{51M}$

Calculation:

The molarity formula is,

  $M=\text{molarity=}\frac{\text{number}\text{of}\text{moles}\text{of}\text{solute}}{\text{volume}\text{of}\text{the}\text{solution}}$

By substituting the given values in the formula and get the number of moles of ions,

  $\begin{array}{c}n=\text{molarity×}\text{volume}\\ \text{=}\text{0}\text{.451}\raisebox{1ex}{$\text{mol}$}\!\left/ \!\raisebox{-1ex}{$\text{L}$}\right.\text{×10}{\text{.2×10}}^{\text{-3}}\text{L}\\ \text{=}\text{4}{\text{.6×10}}^{\text{-3}}\text{moles}\end{array}$

The number of moles of solute is $4.6\times {10}^{-3}\text{moles}$ .

(b)

Interpretation Introduction

Interpretation:

The number of moles of 5.51 L of 0.103 M Na₃PO₄solution needs to be determined.

Concept Introduction:

The molarity is the number of moles of the solute dissolved per liter volume of the solution. It is represented in mathematical term such that,

  $\begin{array}{l}M=\text{molarity=}\frac{\text{number}\text{of}\text{moles}\text{of}\text{solute}}{\text{volume}\text{of}\text{the}\text{solution}}\\ M=\frac{n}{V\left(\text{L}\right)}\end{array}$

Where, n is the number of moles,

L is the volume of the solution.

Answer to Problem 29A

  $0.56\text{7 mol}$

Explanation of Solution

Given information:

The volume is, $V=0.1\text{03L}$

The molarity is, $M=5.\text{51M}$

Formula used:

The molarity formula is,

  $M=\text{molarity=}\frac{\text{number}\text{of}\text{moles}\text{of}\text{solute}}{\text{volume}\text{of}\text{the}\text{solution}}$

Solution:

By substituting the given values in the formula and get the number of moles of ions,

  $\begin{array}{c}M=\text{molarity=}\frac{\text{number}\text{of}\text{moles}\text{of}\text{solute}}{\text{volume}\text{of}\text{the}\text{solution}}\\ n=\text{molarity×}\text{volume}\\ =\text{5}\text{.51}\raisebox{1ex}{$\text{mol}$}\!\left/ \!\raisebox{-1ex}{$\text{L}$}\right.\text{×0}\text{.103L}\\ \text{=}\text{0}\text{.567moles}\end{array}$

The number of moles of solute is $\text{0}\text{.567 moles}$ .

(c)

Interpretation Introduction

Interpretation:

The number of moles of 1.75 mL of 1.25 M CuCl₂ solution needs to be determined.

Concept Introduction:

The molarity is the number of moles of the solute dissolved per liter volume of the solution. It is represented in mathematical term such that,

  $\begin{array}{l}M=\text{molarity=}\frac{\text{number}\text{of}\text{moles}\text{of}\text{solute}}{\text{volume}\text{of}\text{the}\text{solution}}\\ M=\frac{n}{V\left(\text{L}\right)}\end{array}$

Where, n is the number of moles,

L is the volume of the solution.

Answer to Problem 29A

  $2.18\times {10}^{-3}\text{moles}$

Explanation of Solution

Given information:

The volume is, $V=1.7\text{5mL=1}{\text{.75×10}}^{\text{-3}}\text{L}$

The molarity is, $M=\text{1}\text{.25M}$

Calculation:

The molarity formula is,

  $M=\text{molarity=}\frac{\text{number}\text{of}\text{moles}\text{of}\text{solute}}{\text{volume}\text{of}\text{the}\text{solution}}$

By substituting the given values in the formula and get the number of moles of ions,

  $\begin{array}{c}M=\text{molarity=}\frac{\text{number}\text{of}\text{moles}\text{of}\text{solute}}{\text{volume}\text{of}\text{the}\text{solution}}\\ n=\text{molarity×}\text{volume}\\ =\text{1}\text{.25M}\raisebox{1ex}{$\text{mol}$}\!\left/ \!\raisebox{-1ex}{$\text{L}$}\right.\text{×1}{\text{.75×10}}^{\text{-3}}\text{L}\\ \text{=}\text{2}{\text{.18×10}}^{\text{-3}}\text{moles}\end{array}$

The number of moles of solute is $2.18\times {10}^{-3}\text{moles}$ .

(d)

Interpretation Introduction

Interpretation:

The number of moles of 25.2 mL of 0.00157 M Ca(OH)₂ solution needs to be determined.

Concept Introduction:

The molarity is the number of moles of the solute dissolved per liter volume of the solution. It is represented in mathematical term such that,

  $\begin{array}{l}M=\text{molarity=}\frac{\text{number}\text{of}\text{moles}\text{of}\text{solute}}{\text{volume}\text{of}\text{the}\text{solution}}\\ M=\frac{n}{V\left(\text{L}\right)}\end{array}$

Where, n is the number of moles,

L is the volume of the solution.

Answer to Problem 29A

  $3.956\times {10}^{-5}\text{moles}$

Explanation of Solution

Given information:

The volume is, $V=25.2\text{0 mL}=25.20\times {10}^{-3}\text{L}$

The molarity is, $M=0.001\text{57 M}$

Calculation:

The molarity formula is,

  $M=\text{molarity=}\frac{\text{number}\text{of}\text{moles}\text{of}\text{solute}}{\text{volume}\text{of}\text{the}\text{solution}}$

By substituting the given values in the formula and get the number of moles of ions,

  $\begin{array}{c}M=\text{molarity=}\frac{\text{number}\text{of}\text{moles}\text{of}\text{solute}}{\text{volume}\text{of}\text{the}\text{solution}}\\ n=\text{molarity×}\text{volume}\\ =\text{0}\text{.00157}\raisebox{1ex}{$\text{mol}$}\!\left/ \!\raisebox{-1ex}{$\text{L}$}\right.\text{×25}{\text{.20×10}}^{\text{-3}}\text{L}\\ \text{=}\text{3}{\text{.956×10}}^{\text{-5}}\text{moles}\end{array}$

The number of moles of solute is $3.956\times {10}^{-5}\text{moles}$ .