Introduction

Since atoms are so small, how do you know how many atoms or molecules are in a sample?



B13.1 A sample being weighed on a scale
Balanced chemical reaction equations clearly indicate the number of atoms and molecules that are required or produced during a reaction, but how can chemists perform experiments with such minute particles? There must be a way to convert the microscopic amounts into macroscopic (measurable) amounts. This way, chemists could accurately measure exact quantities.

In this lesson, you will look at the concept of the mole and learn how to convert the number of atoms of a substance into the number of moles and into the mass of the sample.

  Targets

By the end of this lesson, you will be able to

  • define the term “mole” as the amount of a chemical species that contains 6.02 x 1023 particles
  • calculate the molar mass of compounds and molecules
  • convert between the amount in moles and the mass of a substance
  • apply the law of conservation of mass to balanced chemical equations

  Intro Activity

How Big Is a Mole? (Not the Animal, the Other One.) @ YouTube TED-Ed 
;


This video will introduce you to the concept of the mole and analogies that will help you understand exactly how big a mole is. This will help get you in the right mindset for this lesson.