http://www.ck12.org Chapter 10. The Mole
10.1 The Mole Concept
Lesson Objectives
- Identify three methods for measuring the amount of matter in a sample.
- Define the mole and its relationship to Avogadro’s number.
- Use Avogadro’s number to convert between moles and the number of representative particles of a substance.
- Relate the atomic mass of an element to its molar mass.
- Calculate the molar mass of a given compound.
Lesson Vocabulary
- Avogadro’s number
- formula mass
- molar mass
- mole
- representative particle
Check Your Understanding
Recalling Prior Knowledge
- What is a conversion factor? What is dimensional analysis?
- What is meant by the atomic mass of an element, and in what units are atomic masses expressed?
- How are the structures of molecular compounds and ionic compounds different?
Chemistry is a quantitative science. It is not enough to simply observe chemical reactions and describe what happens.
Chemists always need to know how much. How many liters of carbon dioxide gas are going to be produced for every
gallon of gasoline that is burned? How many kilograms of the industrial chemical sulfuric acid are produced in a
typical year? How many kilograms of sulfur, oxygen, and water are required to manufacture that much sulfuric acid?
These types of questions show the quantitative nature of chemistry and chemical reactions.
How Much Matter?
If you do any baking, you may have a set of canisters in your kitchen that hold large amounts of flour and sugar
so that they are easy to access when preparing some cookies or a cake. Think about how much sugar is in one
of those canisters. How would you measure it? There are actually multiple answers to this question. One way to
measure the amount of sugar in the canister is to find its mass. Another would be to measure its volume. A third