February 12, 2013
Bell Ringer: Balance K(ClO ) -----> KCl + O
Experiment: C H O + O ------> CO + H O
The decomposition of potassium chlorite, KClO , into KCl and O is used as a source of
oxygen in the laboratory. How many moles of potassium chlorate are needed to produce
15 moles of oxygen gas?
Step 1: Balance Equation
Step 2: Given and Unknown
Step 3: Set up Conversion
with the given times
mol unknown over
mol given (use from
balanced equation).
Hydrogen and oxygen react under a specific set of conditions to produce water according
to the following: 2H + O -----> 2H O .
A.) how many moles of hydrogen would be required to produce 5.0 mols of water?
B.) how many moles of oxygen would be required.
6a.) If 4.50 mol of ethane C H undergo combustion according to the unbalanced equation
C H + O -------> CO + H O , how many mol of oxygen is required?
b.) How many moles of each product are
produced?
February 13, 2013
Practiced Additional Examples.
February 14, 2013
Solving Gram to Gram Stoichiometry Problems
Steps to Solve:
1.) Balance equation
2.) Identify your Unknown and Your Given
3.) Find the Molar Mass of Your Given and Unknown.
4.) Complete your Conversion with the following Equation.
Example 2: Tin II Fluoride (SnF ) is used in some toothpastes. It is made by the following
reaction : Sn + HF -------> SnF + H . How many grams of SnF are produced when 30.0
grams of HF are consumed?
February 15, 2013
Bell Ringer : Get out g-g notes and finish the 2nd example.
Practice Gram to Gram Notes
1.) Laughing gas (nitrous oxide N O) is sometimes used as an anesthetic in dentistry. It
is produced when ammonium nitrate is decomposed according to the following reaction.
NH NO -------> N O + 2H O
When copper metal is added to silver nitrate in solution, silver metal is and copper
(II) nitrate are produced. What mass of silver is produced from 100.0 g of Cu?
February 20-22,2013
Limiting reactants
Step 1: Write out equation and Balance the equation.
Step 2: List givens and unknowns
Step 3: Gram to Gram (2 separate problems)
Step 4: Find the limiting and excess
reactants.
Step 5: Find how much excess reactant
is there. (Another gram-gram problem)
Step 6: Subtract Your original from the used to find
excess.
1.) Zinc and Sulfur react for form zinc sulfide according to the following equation:
8Zn + S -------> 8ZnS
A.) If 2 mol of Zn are heated with 1.00 mol of S , identify the limiting reactant.
B.) How many moles of excess reactant remain?
C.) How many moles of the product are formed?
Pg 321 #26 and paragraph
26.) Sulfuric Acid reacts with Aluminum Hydroxide by a Double Replacement.
A.) If 30.0g of sulfuric acid react with 25.0g of aluminum hydroxide, identify the
limiting reactant.
B.) Determine the mass of excess reactant remaining.
C.) Determine the mass of each product form. Assume 100% yield.
February 28, 2013
Percent Yield
Bell Ringer: What does YIELD mean?
Actual Yield - measured amount of product obtained by a reactant
Percent Yield - the ratio of the actual yield to the theoretical yield multiplied by 100.
Example: N + H ----> NH
A.) if 13.0g N is reacted, what is the theoretical yield of NH ?
B.) If the actual yield is 14.9 g of NH , what was the percent yield?
C.) skipped!
D.) why might the yield be low?
Example 2: C H + Cl -------> C H Cl + HCl
a.) If 10.0 g of C H is reacted, what is the theoretical yield of C H Cl?
b.) If the actual yield is 15.1g of C H Cl, what was the percent yield?
C.) SKIPPED!
d.) Why might the yield be high?
March 1, 2013 bell ringer
H + O -------> H O
a.) If 3.0 g of H is reacted, but 17.9g of H O is produced, what is the percent
yield?
Percent Error: How far away is the yield from 100%.
a.) 85% yield = ________ % error
b.) 107% yield = ________ % error
Practice #1 : Methanol can be produced through the reaction of CO and H in the
presence of a catalyst. If 75.0g of CO reacts to produce 68.4g of CH OH, what is the
percent yield?
CO + H ---------> CH OH