The Mole - Part IIUnit 7: Stoichiometry

Mrs. Callender

Lesson Essential Questions

How do I convert moles to mass, volume, atoms and

molecules?

Mole Map

Grams

mole

Volume of a Gas@ STP

molecules

atoms

Atoms (eleme

nt)

22.4 L

6.02 x 1023

# atoms per

molecule

6.02 x

1023

Factor Label – It’s back…..

How many moles are in 45.7 g of NO2?1. Ask yourself the question –

Can I convert directly from grams to moles?

YES – molar mass has a unit of grams/mole

2. Calculate Molar Mass of NO2.

7

N14.00674

8

O15.9994

Molar mass = 14.01 g + 2(16.00 g) = 46.01 g

Molar mass = 14.01 g + 2(16.00 g) = 46.01 g3. Form conversion

factors.

1 mole46.01 g

46.01 g1 mole

4. Start with your “given” from the original problem.

45.7 g NO2

1

x

5. Use conversion factor that will allow you to “cancel” out grams and give you moles.

6. Cancel out units and calculate using significant digits.

46.01 g NO2

1 mole = 0.993 mole NO2

Factor Label – It’s back…..

How many atoms are in 10.0 moles of Iron (Fe)?1. Ask yourself the question –

Can I convert directly from moles to atoms?

YES – there are 6.02 x 1023 atoms = 1 mole3. Form conversion

factors.

1 m0le 6.02 x 1023 atoms

4. Start with your “given” from the original problem.

10.0 moles Fe 1

x

5. Use conversion factor that will allow you to “cancel” out moles and give you atoms.

6. Cancel out units and calculate using

significant digits.

1 mole Fe6.02 x 1023 Fe atoms

=6.02 x 1024 Fe atoms

6.02 x 1023 atoms 1 mole

Factor Label – It’s back…..How many molecules are in

12.1 g of H2SO4?1. Ask yourself the question –

Can I convert directly from grams to molecules?

NO – You will need two conversion factors. Grams

to moles and moles to molecules.

2. Calculate Molar Mass of H2SO4.

1

H1.00794

8

O15.9994

Molar mass = 2(1.01) + 32.07 + 4(16.00 g) = 98.09 g

Molar mass = 2(1.00)g + 32.00 g + 4(16.00) g = 98.09 g.

3. Form conversion factors.

1 mole98.09 g

98.09 g1 mole

4. Start with your “given” from the original problem.

12.1 g H2SO4

1

x

5. Use conversion factors that will allow you to

“cancel” out grams and give you moles and moles

to give you molecules.

6. Cancel out units and calculate using significant digits.

98.09 g H2SO4

1 mole =

7.42 x 1022

molecules H2SO4

16

S32.066

6.02 x 1023 molecules 1 mole

1 mole . 6.02 x 1023 moleculesx

1 mole

6.02 x 1023 molecules

Factor Label – It’s back…..How many atoms are in 210.0 g

of H2SO4?1. Ask yourself the question –

Can I convert directly from grams to atoms for a molecule?

NO – You will need three conversion factors. Grams to moles, moles

to molecules and molecule to atoms.

2. Calculate Molar Mass of H2SO4.

1

H1.00794

8

O15.9994

Molar mass = 2(1.01) + 32.07 + 4(16.00 g) = 98.09 g

Molar mass = 2(1.00)g + 32.00 g + 4(16.00) g = 98.09 g.

3. Form conversion factors.

1 mole98.09 g

98.09 g1 mole

4. Start with your “given” from the original problem.

210.0 g H2SO4

1

x

5. Use conversion factors that will allow you to

“cancel” out grams and give you moles and moles

to give you molecules.

6. Cancel out units and calculate using significant digits.

98.09 g H2SO4

1 mole =

9.022 x 1024 atoms H2SO4

16

S32.066

6.02 x 1023 molecules 1 mole

1 mole . 6.02 x 1023 molecules

x1 mole

6.02 x 1023 molecules

How do we go from molecules to atoms?Count the number of atoms in one molecule of sulfuric acid.

2H + 1 S + 4 O = 7 atoms in 1 molecule of H2SO4 so…..1 molecule

H2SO4

7 atoms

7 atoms . 1 molecule H2SO4

x

1 molecule H2SO4

7 atoms H2SO4

What conditions need to exist to use the

conversion 1 mole – 22.4 L?Standard Temperature and

Pressure - STPStandard TemperatureStandard Pressure

0 oC

1 atm or 760 torr or 101.3 KPaAt these conditions 1 mole of any

gas has a volume of 22.4 L.

*We will learn how to convert gases at other conditions in the Gas Law Unit.

Factor Label – It’s back…..

How many molecules are in 15.7 L of Iron(II) Oxide?1. Ask yourself the question –

Can I convert directly from liters to molecules?

NO – you will need two conversion factors. Liters to mole and mole to molecules

2. Form conversion factors.

1 m0le 6.02 x 1023 molecules

3. Start with your “given” from the original problem.

15.7 L FeO 1

x

4. Use conversion factor that will allow you to “cancel out moles and give you atoms.

5. Cancel out units and calculate using significant digits.

22.4 L FeO

1 mole FeO =

4.22 x 1023 FeO molecules

6.02 x 1023 molecules 1 mole

1 mole22.4 L

22.4 L1 mole

x 6.02 x 1023 molecules FeO1 mole

FeO