Chemical Quantities IIIA.K.A. Stoichiometry

stoicheion (element; Greek) + metron (measure; Greek)

Quantitative relationship between reactants and products

Created by Jeremias Benjamin Richter in 1792

What is Stoichiometry?

How much water is produced when 1.5 g of C6H12O6 is burned in oxygen?

C6H12O6 + O2 CO2 + H2O; Is it balanced?

C6H12O6 + 6 O2 6 CO2 + 6 H2O

How do we calculate the mass of a product if we know the mass of a reactant?

We have 1.5 grams of C6H12O6; we need a mass-mass conversion pathway

Create a Conversion Pathway

Step 1

Mass of C6H12O6

Moles of C6H12O6

Step 2

Step 3

Moles of H2O

Mass of H2O

Mass of C6H12O6

Molar Mass Moles of C6H12O6

1.5 g C6H12O6 1 mol C6H12O6 = 0.0083 mol C6H12O6

180 g C6H12O6

C6H12O6 + 6 O2 6 CO2 + 6 H2O

Step 1

Moles of C6H12O6

Molar Ratio Moles of H2O

0.0083 mol C6H12O6

6 mol H2O6 = 0.050 mol H2O

1 mol C6H12O6Moles of H2O Molar Mass Grams of H2O

0.050 mol H2O 18 g H2O = 0.090 g H2O

1 mol H2O

Step 2

Step 3

How much aluminum oxide is generated with 2.3 g Al reacting with iron (III) oxide Al + Fe2O3 Fe + Al2O3; is it

balanced? 2 Al + Fe2O3 2 Fe + Al2O3

Another Mass-Mass Conversion

Mass of Al Molar Mass Moles of Al

2.3g Al 1 mol Al = 0.085 mol Al

27 g Al

2 Al + Fe2O3 2 Fe + Al2O3

Step 1

Moles of Al Molar Ratio Moles of Al2O3

0.085 mol Al 1 mol Al2O3 = 0.043 mol Al2O3

2 mol AlMoles of Al2O3 Molar Mass Mass of Al2O3

0.043 mol Al2O3 102 g Al2O3 = 4.3 g Al2O3

1 mol Al2O3

Step 2

Step 3

Mass-Mass ConversionsSmartBoard Exercise

Chemical Quantities III Worksheet Complete the first problem as a

team in your row Complete the second problem as a

pair with the person on your right Complete the next few problems

solo

It’s your turn to Team, Pair, Solo

Read pp. 251-258 Answer problems pg. 262: 31,

33, 35, 39, 40

Homework