1.1 What is Chemistry?

12.1. Mole Ratios http://www.ck12.org

12.1 Mole Ratios

Lesson Objectives

• Be able to calculate the number of moles, molecules, or atoms in a sample.


• Be able to describe mole ratios for reactants and products of a given chemical reaction.


• Understand stoichiometry and stoichiometric coefficients.


• Be able to calculate the moles of reactants needed or products generated for a reaction based on its balanced
  chemical equation.

Lesson Vocabulary

• mole ratio: When the relative amounts of two reaction components are expressed as a ratio.


• stoichiometry: Calculations involving the relative amounts of various reactants and products that participate
  in a chemical reaction.

Check Your Understanding

1. Calculate molar masses for the following compounds:
   a. H 2 O
   b. NH 3
   c. CH 4


2. Calculate the mass (in grams) of the following samples:

a. 2.6 moles of water.

b. 1.4 x 10^23 atoms of sulfur.

Introduction

When making a batch of chocolate chip cookies, a baker must pay careful attention to the amounts of ingredients
he uses. The flour, sugar, butter, and chocolate chips must be measured and used in the correct ratios in order for
the cookies to bake well. If the baker only has a certain amount of flour, only a certain amount of cookies can be
made. Similarly, in chemical reactions, the resulting product is based on the initial moles of reactants present. In this
lesson, you will learn how to calculate and account for the amounts of reactants and products in a given chemical
reaction.