• The coefficients (the number before
a chemical formula) tell you how many molecules of that chemical are used in the reaction. If no number is there, it’s one molecule.
• A chemical equation tells you the fixed ratio
of molecules of reactants the reaction uses, and products that it produces.
• The actual amounts of reactants used or products made in a reaction can be changed but the ratio between them does not
– making twice as much of a product will require twice as much reactants!
• A mole is a precise number of atoms
(six hundred billion trillion!) and it’s used because atomic and molecular masses are measured in grams per mole (written gmol
• Use the chemical equation to find the ratio of reactant moles to product moles and then find their relative masses. Now, you can predict the mass of any reactants required or products expected for any reaction scale.
In this lesson, we will learn:
• How to analyze a balanced chemical equation.
• What a “mole” is and how it is important to understanding chemical reactions.
• How to predict amounts of product made in a reaction with a given amount of reactant.
• How to apply the moles concept with conversion factors to find the mass of reactants and products involved in reactions.