Chemistry Mole and Molar Mass

A series of free High School Chemistry Video Lessons.

In ths lesson, we will learn

  • Chemistry Mole
  • Molar Mass
  • Law of Conservation of Mass
  • Empirical Formula - Molecular Formula



Chemistry Mole
In chemistry, the mole, also called Avogadro’s Number, is a unit that is useful in converting between atomic mass and molar mass. One mole is 6.02 x 1023 of something, which was derived from the number of atoms in 12 grams of carbon-12.

The meaning and functionality of Avogadro's number in chemistry.



The Mole and Avogadro's Number



Molar Mass
The molar mass of a substance is the mass of one mole of that substance. Because of the nature of the mole, the atomic mass of an element in atomic mass units is equal to the molar mass of that substance in grams. Molar mass is useful in finding the number of moles of a substance within a given sample.

How to find and use molar mass.



This lesson introduces molar mass as the mass of one mole of a substance. Examples of mole to mass, and mass to mole conversions are shown using molar mass (or gram formula mass.)



Law of Conservation of Mass
The law of conservation of mass states that mass is neither created nor destroyed. In a closed system, mass of reactants is equal to mass of products. The law of conservation of mass is related to the law of conservation of matter.

Understanding the law of conservation of mass.



Empirical Formula - Molecular Formula
An empirical formula is the lowest ratio of the atoms within a molecule. The empirical formula is accurate when describing ionic compounds, which cannot be broken into a single molecule unit. But when describing covalent compounds we use a molecular formula which describes the atoms within a single molecule. The ratio of atoms within a molecular formula is the same as that in the empirical formula, but it is not reduced. Molecules with the same empirical formula have the same percent composition.

Understanding the differences between empirical and molecular formulas.



Introduction to molecular and empirical formulas. Calculating molecular mass.




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