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Difference Between Molar mass and Molecular mass

In chemistry the substance is usually measured using molecular mass and molar mass. They are very important concepts in chemistry. Expression of molar mass is grams per mole. It can also be expressed as kilogram per mole. Molecular mass is expressed in atomic mass units.

Molecular mass:

Molecular mass of a compound is defined as the mass of one molecule. Molecular mass differs because of the isotopes. The unit in which molecular mass is measured is amu. amu stands for atomic mass units.

Molar mass:

It is defined as the mass of substance for a given amount. The amount of molecules or atoms or compounds present in one mole of substance is given by this. Molar mass SI unit is g/mol

To make you understand how molar mass and Molecular mass are different from each other, here are the some of the major differences between molar mass and molecular mass:

Difference between Molar mass and Molecular mass
MOLAR MASS MOLECULAR MASS
Refers to mass of one mole of a substance Refers to the mass of sum of the atomic masses of all the atoms present in a molecule
Also known as molecular weight It determines the mass of a single molecule
SI unit is g/mol to use in higher calculations Measured in amu
It is defined as the mass of Avogadro number of atoms/molecules or compounds Defined as the sum of the atomic masses of all the atoms present in a molecule of a substance.
Measurement given to compounds, atoms or molecules Determined only in molecules
Less accurate than molecular mass Accurate to use in higher calculations
Example: Mass of 1 mole of oxygen is 15.9994 grams. Therefore, the molar mass = 15.9994 g/mol Example:

Molecular mass of Ca(OH)2 = 74 atomic mass units

These were some important difference between molecular mass and molar mass. To know differences between other topics in chemistry you can register to BYJU’S or download our app for simple and interesting content. India’s largest k-12 learning app with top-notch teachers from across the nation with excellent teaching skills. Find notes, question papers for other subjects like Mathematics, Physics, Biology and various competitive exams as well. Enjoy learning with great experience. Learning is no more boring with BYJU’S.

Frequently Asked Questions – FAQs

Why do we need the Mole concept?

It allows the chemist to weigh quantities of two substances, say iron and sulphur, in order to obtain equal numbers of iron and sulphur atoms. A mole of a substance is known as a material mass containing the same number of basic units as atoms in exactly 12,000 g of 12C.

Why is Avogadro’s number called a mole?

The density of one mole in grams is the weight in atomic mass units of that element. The French physicist Jean Perrin called the number of units in the sum of one mole Avogadro a few years later. For example, one mole of water molecules contains 6.022140758 x 1023 molecules.

What is the use of the mole concept?

The mole is the chemical quantity unit. This connects the atom with the macroscopic quantities of material with which we work in the laboratory. It allows the chemist to weigh quantities of two substances, say iron and sulphur, in order to obtain equal numbers of iron and sulphur atoms.

What does Avogadro’s law state?

The law of Avogadro, also referred to as the rule of Avogadro or the theory of Avogadro, is an experimental gas law that relates the volume of a gas to the amount of gas present. The law of Avogadro states that “equal quantities of all gases have the same number of molecules at the same temperature and pressure.”

How many moles are in a mole?

The mole, abbreviated mol, is an SI unit that measures a specific substance’s number of particles. One mole is equal to 6.02214179 or other elementary units like molecules.

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2 Comments

  1. What is the relationship between molar mass and formula mass?

    1. The formula mass of a compound is the sum of the atomic masses of the atoms in its empirical formula. On the other hand, the molar mass of a compound is the mass of one mole of that compound.

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