Chapter 3, Problem 3.23P

(a)

Interpretation Introduction

Interpretation:

The mass fraction of chlorine $\left(\text{Cl}\right)$ in calcium chlorate is to be calculated.

Concept introduction:

Molar mass is defined as the mass of $1\text{ mol}$ of a chemical substance in grams. The molar mass of a compound is calculated by the addition of the molar mass of each element multiplied by its number of atoms present in the chemical formula.

The mass fraction of an element in a compound is defined as the ratio of the sum of the masses of all the atoms of that element to that of the mass of one mole of compound.

The steps to calculate the mass fraction of an element are as follows:

Step 1: Determine the molar mass and the formula of the compound. From the formula, determine the relative number of moles of each element. To determine the mass fraction of an element, calculate its total mass. The formula to calculate the total mass of an element A present in the compound is as follows:

$\text{Total mass of A}=\left(\text{Moles of A in formula}\right)\left(\begin{array}{l}\text{Molar mass of A }\\ \text{in g/mol}\end{array}\right)$ (1)

Step 2: To calculate the mass fraction of an element A, take the ratio of the total mass of element A and the mass of one mole of compound. The formula to calculate the mass fraction of an element A is as follows:

$\text{Mass fraction of A}=\frac{\text{Total mass of A }\left(\text{g}\right)}{\text{Mass of 1 mol compound }\left(\text{g}\right)}$ (2)

(b)

Interpretation Introduction

Interpretation:

The mass fraction of nitrogen $\left(\text{N}\right)$ in dinitrogen trioxide is to be calculated.

Concept introduction:

Molar mass is defined as the mass of $1\text{ mol}$ of a chemical substance in grams. The molar mass of a compound is calculated by the addition of the molar mass of each element multiplied by its number of atoms present in the chemical formula.

The mass fraction of an element in a compound is defined as the ratio of the sum of the masses of all the atoms of that element to that of the mass of one mole of compound.

The steps to calculate the mass fraction of an element are as follows:

Step 1: Determine the molar mass and the formula of the compound. From the formula, determine the relative number of moles of each element. To determine the mass fraction of an element, calculate its total mass. The formula to calculate the total mass of an element A present in the compound is as follows:

$\text{Total mass of A}=\left(\text{Moles of A in formula}\right)\left(\begin{array}{l}\text{Molar mass of A }\\ \text{in g/mol}\end{array}\right)$

Step 2: To calculate the mass fraction of an element A, take the ratio of the total mass of element A and the mass of one mole of compound. The formula to calculate the mass fraction of an element A is as follows:

$\text{Mass fraction of A}=\frac{\text{Total mass of A }\left(\text{g}\right)}{\text{Mass of 1 mol compound }\left(\text{g}\right)}$