Chapter 10, Problem 102A

Interpretation Introduction

Interpretation:

The difference between atomic mass (amu) and molar mass (g) should be explained

Concept introduction:

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 102A

Atomic mass (amu)	Molar mass (g)
It is expressed in amu (atomic mass unit).	It is expressed in g/mole.
It is defined as the mass of one individual atom of a substance.	It is defined as the mass of one mole of a substance.
It is equal to the 1/12th of the mass of carbon-12.	It is equal to the addition of molar masses of atoms in g/mole.

Explanation of Solution

Difference between atomic mass (amu) and molar mass (g):

Molar mass of the compound or element is equal to the mass in grams of one mole of that molecule or substance. It is a measured in g/mole.

Molar mass of the compound is calculated by the addition of molar masses of atoms in g/mole present in that compound.

Atomic mass unit is defined as the unit mass which is equal to the 1/12^th of the mass of carbob-12 atom. It is expressed in a.m.u and it is calculated by the addition of atomic masses present in the substance.

Therefore, according to above definition, molar mass is defined as the mass in gram of 1 mole of a substance whereas the atomic mass is the mass of one individual atom of a substance. The unit of molar mass is g/mole and atomic mass is amu.

Numerically, atomic mass in a.m.u is equal to the mass in gram of one mole of a substance.

For an example:

Atomic mass of sodium chloride is calculated as:

Formula of sodium chloride = $\text{NaCl}$

Atomic mass of sodium = 23 amu.

Atomic mass of chlorine = 35.45 amu.

Total atomic mass of sodium chloride = $\text{23 amu +35}\text{.45 amu}$

= $\text{58}\text{.45 amu}$

Molar mass of sodium = 23 g/mole

Molar mass of chlorine = 35.45 g/mole

Total molar mass of sodium chloride = $\text{23 g/mole +35}\text{.45 g/mole}$

= $\text{58}\text{.45 g/mole}$