Stoichiometry 1
OCTOBER 15 & 16 2012
MS. BOON CHEMISTRY
Objective:
 Catalyst:
•I can create mole
 A cookie recipe requires 1 cup of
ratios from a
balanced chemical
equation and
perform mole to
mole conversions.
•Agenda:
•Catalyst
•Notes:
Stoichiometry
•Practice: Mole
Ratios
•Notes: Mole to
mole
•Practice: mole to
mole
•Exit Slip
sugar, 2 cups of flour, 1 stick of
butter and 3 eggs.
 How much of each ingredient do
you need in order to double the
recipe? Explain your answer.
Today’s Schedule
OBJECTIVE:
•I C A N C R E A T E M O L E R A T I O S F R O M A
BALANCED CHEMICAL EQUATION AND
PERFORM MOLE TO MOLE CONVERSIONS.
•A G E N D A :
•C A T A L Y S T
•N O T E S : S T O I C H I O M E T R Y
•P R A C T I C E : M O L E R A T I O S
•N O T E S : M O L E T O M O L E
•P R A C T I C E : M O L E T O M O L E
•E X I T S L I P
Notes: What is stoichiometry?

Stoichiometry is
the study of the
relationships
between
quantities of
substances in
chemical
reactions.
Where are we going with this?

By the end of the unit, we will be able to solve questions like this:
 Mustard gas (chemical warfare agent used in World War 1)
is synthesized by the reaction of sulfur dichloride and
ethylene.
SCl2 + 2 C2H4 → (ClCH2CH2)2S
 If you have 10 g SCl2 and 100 g C2H4, how many grams of
mustard gas can you make? Why?
Where are we going with this?
What is a Ratio?
• A "ratio" is just a comparison between two
different things
Ex.: A cookie recipe requires 1 cup of sugar, 2 cups of
flour, 1 stick of butter and 3 eggs.
•What is the ratio of sugar to flour?
•What is the ratio of butter to eggs?
•Ratio of eggs to flour?
•What if you wanted to “double” the recipe?
You can use ratios for moles too!
-Balance the following reaction, label the
reactants and the product.
Mg +
O2 
2 Mg + O2 
MgO
2 MgO
Finding the molar ratio -- Example 1:
2 Mg + O2 
2 MgO
1. What is the ratio of moles Mg atoms to moles O2
molecules?
A: There are 2 moles Mg atoms for every 1 mole
O2 molecules.
The ratio is 2:1.
Write this ratio as a fraction: 2 mol Mg
1 mol O2
Example 2:
CH4 + 2 O2 → CO2 + 2 H2O
1 mol CH4
2 mol O2
1. What is the ratio of moles CH4 to moles O2?
2. What is the ratio of moles O2 to moles CO2?
2 mol O2
1 mol CO2
3. What is the ratio of moles H2O to moles CH4?
4. What is the ratio of moles CO2 to moles H2O?
2 mol H2O
1 mol CH4
1 mol CO2
2 mol H2O
Quick Check Question
 Do the following problem in your notes.
2 NI3  N2 + 3 I2
 What is the mole ratio of NI3 to N2?
 Vote for your answer:
1) 1 mol NI3
2 mol N2
3) 2 mol NI3
1 mol N2
2) 2 mol NI3
2 mol N2
4) 3 mol NI3
2 mol N2
Practice Problems Set 1
 Complete the following problems in your notes.
 Give the mole ratio between the two compounds that






are in bold red.
1) 2 FeO + 1 C  2 Fe + 1 CO2
2) 2 NO + 1 O2  1 NO2
3) 1 CH4 + 4 S  1 CS2 + 2 H2S
Balance the equations and then give the ratio
between the two compounds in bold red.
4)__PCl3 +__H2O __H3PO3 +__HCl
5)___Xe + ___F2  ___XeF4
6)__Al +__HCl __AlCl3 +__H2
Mole to Mole Conversions: Example 1
2 Mg +
O2 
2 MgO
 How many moles of MgO can be made from 12 moles
of Mg?
 What are we converting? Mol Mg to Mol MgO
 Step 1: Write the mole ratio with the unknown units on
top.
 Step 2: multiply by the given moles.
2 mol MgO
2 mol Mg
X
12 mol Mg
=
12 mol MgO
Mole to Mole Conversions: Example 2
CH4 + 2 O2 → CO2 + 2 H2O
 How many moles of CH4 are needed to form 30 moles of
H2O?
 What are we converting? Mol H2O to Mol CH4
 Step 1: Write the mole ratio with the unknown units on top.
 Step 2: multiply by the given moles.
1 mol CH4
2 mol H2O
X
30 mol H2O
=
15 mol CH4
Quick Check Question
 Do the following problem in your notes.
2 NI3  N2 + 3 I2
 How many moles NI3 are required to produce 10 moles
N2?
 Vote for your answer:
1) 10 mol NI3
3) 5 mol NI3
2) 20 mol NI3
4) 40 mol NI3
Mole to Mole Conversion Practice
 Complete the worksheet problems on your notes.
 Work quietly with the people around you.
 Show all your work.
 Tonight’s HW: Read p. 302 – 305; Do practice
problems p. 304 #1 & 2, p. 311 #1, 4(a), 6.
Exit Slip
2 KClO3 (s) → 2 KCl (s) + 3 O2 (g)
What is the mole ratio of KCl to O2?
2. What is the mole ratio of KCl to KClO3?
3. How many moles O2 will be produced from 4 moles
KClO3?
4. How many moles KClO3 are required to produce 32
moles KCl?
1.