The Hamburger My recipe for a bacon double cheeseburger is: 1 hamburger bun 2 hamburger patties 2 slices of cheese 4 strips of bacon Based on this recipe: If I have five bacon double cheeseburgers: How many hamburger buns do I have? How many hamburger patties do I have? How many slices of cheese do I have? How many strips of bacon do I have?

Stoichiometry, Ch 9 Chemistry I-A 4-6 days This unit will require you to have more direct instruction from your Teacher. Please use your class time wisely!

Essential Questions for Ch. 9 (Don’t copy or turn in. This is a great test review!) What do the coefficients of a balanced equation represent? How do you work basic stoichiometry problems? How do you convert grams to grams or mixed units using the ratio of coefficients? What are actual yield, theoretical yield and percent yield? How can you determine the percent yield of salt (NaCl) in the reaction of sodium hydrogen carbonate and hydrochloric acid? What are limiting reactants and how are they related to equations and daily applications?

Stoichiometry- STOY-KEE-AHM-EH-TREE A mathematical process that uses the balanced chemical reaction Stoichiometry is the measuring and calculating of the amounts of elements and compounds involved in a chemical change.

The Key to Stoi-key-ometry is in the Coefficients To calculate the amounts, we use the COEFFICIENTS of the chemical equation. The coefficients in a balanced reaction represent the ratio of MOLES, LITERS and MOLECULES. It does NOT REPRESENT the ratio of grams.

The Steps 1.Balance the equation. 2.Write down the given and what is wanted and label this information on the equation 3.Convert to moles if needed (not necessary if you are going from mole to mole, liter to liter or molecule to molecule)

Steps, cont 4. Multiply by the ratio of: coefficient of want/coefficient of given 5. Convert to the unit that is wanted in the problem

To be successful You must have a balanced equation You must show your work. That includes units and names of compounds No work, no credit, no kidding!

Examples-See your teacher! Mole to Mole Molecule to Molecule Liter to Liter Mass to Mass Mixed Units

Percent Yield-measures efficiency THEORETICAL YIELD – How much product should be produced (calculated from stoichiometry problem) ACTUAL YIELD - How much product was actually produced in the lab (what you actually produced) Formula

Example #3 __Mg + _CrCl 3  ___MgCl 2 + ___Cr In a lab 50.0g of Mg reacted with CrCl 3 to produce MgCl 2. If g was produced in lab, what was the percent yield of MgCl 2 ? Theoretical yield – Actual yield – % yield = actual/theoretical x 100

Limiting Reactants A limiting reactant is the starting compound or element that controls how much product is made. It is the one that runs out first.

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