January
6
Ch. 9 Notes:
Stoichiometry –
Mole/Mole and Mole
to Mass Calculations
7
Ch. 9 Notes:
Stoichiometry –
Mass/Mass Calc. and
Combination
8
Chapter 9 In-Class
Team Review WS
9
Ch. 9 Notes: Limiting
reagents
HW: LR
10
Ch. 9 Notes: Percent
Yield
HW: % Yield
Chapter 9 WS #3
HW: Mole to Mole
and Mole to Mass
HW: Mass to Mass
13
Lab in Room
Percent Yield
14
Finish Lab
and
Quiz
15
Tums Lab
With Percent Yield
16
Go Over Quiz
Chapter 9 Review
17
Chapter 9 Test
STOICH
Bell Work
Stoichiometry- Chapter 9
Stoichiometry –
study of calculations of quantities in chemical reactions using balanced
chemical equations.
Balanced Equation 2 Mg
+
1 O2

2 MgO
Moles
2 moles Mg +
1mole O2

2 moles MgO
Mass
46.3 g Mg
+
32 g O2

78.3 g MgO
Liters
44.8 L Mg
+
22.4 L O2

44.8 L MgO
The mole ratios can be obtained from the coefficients in the balanced chemical equation.
Mole ratios can be used as conversion factors to predict the amount of any reactant or
product involved in a reaction if the amount of another reactant and/or product is known.
The New Mole Map!
__________________________________________________________________________________
Mole - Mole Calculations – Mole ratios are used to calculate the number of moles of product from
the given number of moles of reactant, or vice versa.
Example: Calculate the number of moles of Na2O that will be produced when 5.00 moles of Na
completely react with oxygen gas.
1) Write the equation: _____________________________________________________
2) Given: ___________________
3) Want: ____________________
__________________________________________________________________________________
Mole-Mass Calculations - We use mole ratios from balanced chemical equations and the molar
conversions from Ch. 7 to calculate amounts (grams) of substances needed or produced in chemical
reactions.
Example: How many grams of KClO3 must decompose to produce KCl and 1.45 moles O2?
1) Write the equation: _______________________________________________
2) Given: ___________________
3) Want: ____________________
__________________________________________________________________________________
Mass-Mass Calculations - Same as mole-mass calculations, with an additional step of converting
mass to moles.
Example: When 24.0 g of Na are mixed with Cl2, are 52.0 g of NaCl produced?
1) Write the equation: _______________________________________________
2) Given: ___________________
3) Want: ____________________
Example: CaCO3, limestone, is heated to produce calcium oxide, CaO, and CO2. What mass of
limestone is required to produce 156.0 g of CaO?
1) Write the equation: _______________________________________________
2) Given: ___________________
3) Want: ____________________
__________________________________________________________________________________
Combination Calculations:
Example: At STP, how many grams of oxygen are needed to produce 19.8 L SO3 according to
the balanced equation below?
2SO2 (g) + O2 (g)  2SO3 (g)
1) Given: ___________________
2) Want: ____________________
__________________________________________________________________________________
Reactants in Excess and Limiting Reactants
•
Limiting Reactant - the reactant that is used up in a reaction. When you run out of a
reactant, the reaction stops and no more product is formed.
•
Excess Reactant - the reactant that is not used up in a chemical reaction.
•
The limiting reactant determines the amount of product formed.
Steps to determining limiting reactant:
1.
Find out how much could be produced from each amount of reactant.
2.
Whichever produces less is limiting the amount produced. It is therefore the Limiting
Reactant.
Example: If 6.70 mol of Na reacts with 3.20 mol Cl2, what is the limiting reagent? How many
moles of NaCl will be produced?
Na
+
Cl2 → NaCl
***notice 2 givens, both reactants***
To determine how much excess reactant is left after a reaction, subtract how much of the excess
reactant reacted from how much excess reactant you started with.
Example: When 0.50 mole of aluminum reacts with 0.72 mole of iodine, to form aluminum
iodide, AlI3(s), what mass of AlI3 is produced? How much of the excess reactant will remain?
Separate this problem into two different steps.
1. Find the limiting reactant and amount produced (as in previous example)
2. Find amount in excess (left over)
2 Al
+
3 I2 →
2 AlI3
Limiting Reactant ________
Excess left over in grams ____________
__________________________________________________________________________________
Percent Yield:
Theoretical Yield – The maximum amount of product that could be formed from given
amounts of reactants. (What you should get).
Actual Yield - amount of product actually obtained in the reaction (What you really get).
(Actual/Theoretical) x 100 = % Yield
Example: If 12.5 g of copper are reacted with an excess of chlorine gas, then 25.4 g of copper(II)
chloride, CuCl2(s), are obtained. Calculate the theoretical yield and the percent yield.
1) Write the equation: ___________________________________________________________
2) Find the theoretical yield (amount you “should get”)
3) Now do the % yield equation