What is Molar Mass?

Molar Mass is the mass in grams of one mole of the compound. In chemistry, the word "mole" refers to a specific quantity. A mole contains a vast, extremely large number of items (6.0221415 x 10²³ ). Chemists simultaneously work on samples big enough to work with in the lab and on the level of individual atoms. They frequently require knowledge of the number of atoms or molecules in the sample they are working with to go back and forth between these two scales. Molar mass functions as the conceptual link between these two scales.

Definition Avogadro's number (6.022140857×10²³ mol) of molecules or formula units make up one mole of a substance. “The mass of one mole of a substance in grams is known as its molar mass. Molar mass is measured in grams per mole, or g/mol.” In other words, the molar mass is the sum of the mass of all the atoms that make up a mole of a specific molecule, expressed in grams.

Unit of Molar Mass The units of molar mass are grams per mole, which is abbreviated as g/mol or g mol^-1.

How to Calculate the Molar Mass of a Compound?

The term "compound" refers to a substance that is made up of more than one element. The molar mass of a compound is calculated as follows:

1. Find out how many of each type of atom are present in the compound by using the chemical formula of that particular compound. For example, In the compound of water, the chemical formula of water is H₂O.

2. Multiply each element's atomic weight taken from the periodic table by the number of that element's atoms in the compound.

3. Add everything together, then write the result in terms of grams/mole.

Video for reference: https://www.youtube.com/embed/c_zHROisdP4

Sample Calculations

Molar Mass of Sodium Chloride Chemical formula of Sodium Chloride = NaCl

Molar mass = 22.987 × 1 + 35.543 × 1 = 58.53 g/mol

Molar Mass of Sodium Carbonate Chemical formula of Sodium Carbonate = Na₂CO₃

Molar mass = 22.987 × 2 + 12.0107 × 1 + 15.994 × 3 = 45.974 + 12.0107 + 47.982 = 105.9667 ≅ 106 g/mol

Molar Mass of Ethanol Chemical formula of Ethanol = C₂H₅OH

Molar mass = 12.0107 × 2 + 1.0079 × 6 + 15.9994 = 24.0214 + 6.0474 + 15.9994 = 46.0682 ≅ 46.07 g/mol

Molar Mass of Acetic acid Chemical formula of Acetic acid = CH₃COOH

Molar mass = 12.0107 × 2 + 1.0079 × 4 + 15.9994 × 2 = 24.0214 + 4.0316 + 31.9988 = 60.0518 g/mol

Difference between Molar mass and Molecular mass

Importance of Molar Mass The molar mass is typically used in chemistry to determine the mass of a substance from the number of moles or to determine the number of moles from the mass of a substance. Here are some examples of how molar mass can be used:

• If you know a substance's molar mass and the number of moles, you may multiply the molar mass by the moles to determine the substance's mass.

• If you know the molar mass of a substance and the mass of the substance, you can calculate the number of moles of that substance by dividing the mass by the molar mass.

• Molar mass can be used to estimate a solution's concentration.

• To convert between mass and volume for gases, one can use the concept of molar mass.

Key Takeaways Key points

• The mass of a specific chemical element or chemical compound (g) divided by the amount of substance is known as the molar mass (mol).

• Since it is not possible to quantify the number of moles directly, molar mass acts as a link between the mass of material and the number of moles.

• For bulk quantities, the molar mass makes it possible to convert between a substance's mass and its amount.

• The term molar mass is also known as molecular weight.

Key Terms

• Avogadro's number: Avogadro's number or Avogadro's constant refers to the number of units contained in one mole of any substance. The value is 6.022140857×10²³. Depending on the nature of the reaction and the substance, the units may be electrons, ions, atoms, or molecules.

• Mole: In chemistry, a mole, sometimes spelled mol, is a common scientific measurement unit for significant amounts of very small objects like atoms, molecules, or other predetermined particles. The mole designates 6.022140857×10²³ units, which is a very large number.

FAQs on Molar Mass Define molar mass. The mass of a substance per mole is known as its molar mass. The standard unit of measurement is grams per mole (g/mol). How is the molar mass determined? The atomic masses of the constituent elements and the total number of atoms in the substance must be known in order to compute the molar mass of the substance. The atomic masses of all the substance's atoms are then added up to determine the molar mass. What is a molecule's molar mass? The total atomic masses of all the atoms in a molecule make up the molecule's molar mass. For instance, water (H₂O), which is composed of two hydrogen atoms (each with a mass of 1.008 g/mol) and one oxygen atom (with a mass of 15.999 g/mol), has a molar mass of 18.015 g/mol. What are the uses for molar mass? The molar mass is used in several disciplines, such as chemistry, physics, and engineering. It is frequently used to determine the concentration of solutions as well as to convert between mass and moles. Do molar mass and molecular weight correspond? Yes, molar mass and molecular weight are frequently used interchangeably. In both instances, they are referring to the mass of a material per mole of that substance.