CHEM 0010 Unit


UNIT # 8
Introduction
Objectives
Reading
8.1 Conventions and Symbols 8.2 Balancing Chemical Equations 8.3 Methods of Balancing Equations 8.4 Types of Chemical Reactions 8.5 Calculations Based on Chemical Equations
Problems 1 \| 2 \| 3 \| 4

CHEMICAL REACTIONS

8.3 - Methods of balancing chemical equations

8.3.2 - Balance Algebraically

Take out a piece of paper and a pencil and go through this example with me. We will use algebra to solve for the coefficients. It's a 6-step process.

When propyl alcohol, CH₃CH₂CH₂OH, burns in air, it reacts with oxygen, O₂, to form carbon dioxide, CO₂, and water, H₂O. Write the balanced chemical reaction.

If you think you know how to do this, skip to see the balanced chemical equation.

Otherwise, let's begin:

Step 1	Identify the reactants and products.
Step 2	Write the unbalanced chemical equation.
Step 3	Assign variables as coefficients for each substance in the chemical equation.
Step 4	Determine the number of each type of atoms on each side of the arrow.
Step 5	Write out the algebraic equations and solve for the coefficients.
Step 6	Make sure that all the coefficients are whole numbers. Multiply all the coefficients by an appropriate factor to convert any fractions to whole numbers.

The balanced chemical equation is:

2 CH₃CH₂CH₂OH (l) + 9O₂ (g) 6CO₂ (g) + 8H₂O (l)

Section 9.3
Guidelines for Balancing Chemical Equations ..p219
Section 9.4
Examples Involving Balancing Equations ..p221

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