Chapter 10 notes

Chapter 10 NotesAll About the Mole

Objectives• Convert a quantity of a chemical between

moles, mass (g), particles, and volume.• Calculate the molar mass for any

compound.

Hi, I’m Monty Mole. I’ll be your guide for

this unit….The evil monkey

from the closet has the day off….

Molar MassStep 1: Find each atom on the periodic

table.Step 2: Find out how much each atom

weighs. (atomic mass)Step: 3 Multiply the mass by the number of

atoms in the molecule.Step 4: Add them all up!

Try it out!Find the molar masses of

the following:NaCl, SO3, H2O, PCl3

NaCl 58 g/mol

SO3 80 g/mol

H2O18 g/mol

PCl3136 g/mol

What is a Mole?•A mole is a measurement of matter.•It is used for counting things that require large numbers.•The mole is just another unit of measure like feet or grams.

The number that we use to equal a mole is called Avogadro’s number.This number is6.02 X 1023

Everything Goes Through The Mole!

• To convert from one unit to another, you must use the mole as an intermediate step.

•In other words…you might need a “two-step” conversion problem.

What is a “Two-Step” Conversion Problem?

• Two conversion factors

–One to convert from given unit to moles

–One to convert from moles to wanted unit

Mole Road Map (4 LIFE)

Mass

Representative Particles

Mole

22.4 L

1 mol

1 m

ol

22.4

L

1 mol

6.02x10 23 particles

Molar mass

1 mol

1 m

ol

Mola

r mas

s

6.02x1023 particles

1 mol

(grams) (atoms, molecules, or formula units)

Volume

of gas

(STP)

Here’s An Example

Calculate the number of molecules in 60.0 g NO2.

Given: 60.0 g NO2

1st Conversion: Molar Mass Equality

molar mass NO2 : 46.01 g46.01 g = 1 mol

2nd Conversion: Definition of Mole Equality1 mol = 6.02 x 1023 molecules

So here’s the equation:

60.0 g NO2 x 1 mol x 6.02 x 1023 molecules =

46.01 g NO2 1 mol

7.85 x 1023 molecules NO2

Another Example

Calculate the volume, in liters, of 3.24 x 1022 molecules of Cl2 (STP).

1.21 L Cl2

3.24 x 1022 molecules Cl2 x 1 mol x 22.4 L Cl2 = 6.022 x 1023 molecules 1 mol

Now let’s practice!!! HAAA AAHAHAAAA!

How many moles is 2.80 X 1024 atoms of silicon?

How many moles is 2.17 X 1023 particles of bromine?

How many moles are in 20 grams of NaCl?

Determine the volume in liters of 5 moles of hydrogen gas.

SUM IT UP!

• How many moles are in 100 grams of water?