Measuring Matter
Section 11.1
Chemistry
Objectives
Describe how a mole is used in
chemistry.
Relate a mole to common counting units.
Convert between moles and number of
representative particles
Counting Particles
A
A
A
A
pair is always 2 objects
dozen is 12
gross is 144
ream is 500
If I plant 3 dozen roses, how many
roses will I have?
Counting Particles
Chemists use a counting system that
uses a very large number.
The mole is the SI base unit used to
measure the amount of a substance.
Counting Particles
The mole is used to count particles
that are very small.
– Molecules, atoms, formula units,
electrons, or ions.
The mole is equal to Avogadro’s
number: 6.022 x 1023
This is a HUGE number.
– 602,000,000,000,000,000,000,000
Converting Moles to Particles
and Particles to Moles
Suppose you buy 3.5 dozen roses.
How many roses do you have?
We must go back to conversion
factors.
3.5 dozen x 12 roses/1dozen = 42
roses.
Conversion Factor!
6.022 x 1023 representative particles
1 mole
Example Problem
If I have 3.5 mol of sucrose, how
many molecules of sugar do I have?
Start with what you are given in the
problem.
3.5 mol of sucrose
Then determine the conversion factor
What do you want to end up with?
Representative particles
Flip the conversion factor so
representative particles is on top
Then write your problem out
3.5 mol sucrose x 6.022 x 1023 representative particles
1 mol sucrose
2.11 x 1024 molecules of sucrose.
Practice Problems
Pg. 311
Assignment
Worksheet on Converting Moles to
Particles and Particles to Moles