Chapter U4.77, Problem 1E

Interpretation Introduction

Interpretation:

The process for determining the molar mass of sodium chloride $\text{NaCl}$ should be calculated.

Concept Introduction:

The ratio of mass of the given compound to the number of moles of compound is known as molar mass.

Mole is SI unit which is used to measure the quantity of the substance. It is the quantity of a substance which contains same number of atoms as present in accurately 12.00 g of carbon-12 is known as mole.

The one mole of any substance is equal to the Avogadro number i.e. $6.022\times {10}^{23}$ atoms.

Answer to Problem 1E

Molar mass of sodium chloride is $58.44\text{ g/mole}$ and it is calculated by the sum of atomic masses of sodium and chlorine atom.

Explanation of Solution

Molar mass of the molecule is calculated by the sum of the masses of atoms present in the molecule.

The given molecule is $\text{NaCl}$ .

First step is to determine the number of atoms present in the molecule.

In the given molecule that is sodium chloride, number of atoms is two that is one sodium atom and one chlorine atom.

Second step is to determine the atomic masses of an atom.

From periodic table, atomic mass of sodium = 22.98 g/mole

Atomic mass of chlorine = 35.35 g/mole

Now, molar mass of sodium chloride is calculated as:

Molar mass of $\text{NaCl}$ = $\begin{array}{l}\text{Number of sodium atom }\times \text{ Molar mass of sodium atom + }\\ \text{Number of chlorine atom }\times \text{ Molar mass of chlorine atom}\end{array}$

Put the values,

Molar mass of $\text{NaCl}$ = $\text{1 }\times \text{ 22}\text{.98 g/mole + 1}\times \text{35}\text{.45 g/mole}$

= $58.44\text{ g/mole}$

Therefore, molar mass is calculated by sum of mass of atoms present in the sodium chloride molecule.