Mass to Mass + Combustion

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How to solve a M2M problem
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How to solve a M2M problem
-write balanced equation
-determine the given
-determine the asked
-find molar mass, use mol ratio, convert asked to grams.
What is Molarity?
Describes the # of moles of solute dissolved in a # of liters of solution (liters of solvent)
Molarity Equation
Molarity equation:
Molarity= # moles of solute /L of solution
Example of Molarity Problem
What is the molarity of a NaCl solution that contains 289 g dissolved in 890 mL of water?
289 g NaCl x 1 mol / 58.5 g= 4.94 moles

890 mL x 1 L /1000. mL =0.8901 L

M=4.940 moles / 0.9801 L
= 5.6 moles/L
Molarity with M2M Problem
Step 1: Find moles given
M=mole/Lā†’ # of moles given
(Molarity problem first to find moles)
Step 2: find mole asked using mol ratio
# moles G x mol A /mol G= # moles A
(just do mole ratio from equation)
Step 3: find asked
M=mol AL
or moles A x molar mass A1 mol
(do fence post for moles asked using the number from mole ration equation, to get final answer in grams).
-Do the M2M problem (only to mol ratio) to get # of moles.
-Do a Molarity problem with moles found and L (given in problem).
Limiting Reagent (LR)
-Reactant we don't have enough of
-Runs out-reaction stops
-Determines the amount of product that could form
-it is the reactant that is totally consumed during the reaction
Excess Reagent (ER)
-Reactant that's left over after reaction
-Not all of it is used up.
Theoretical Yield
-The amount of product that could form when the limiting reagent runs out
-The maximum amount that could form
Example: 3 scoops of ice cream + 1 cone =1 ice cream cone.
-The limiting Reagent is the cones, so the theoretical yield is 1 ice cream cone because that is how much formed when the limiting reagent (waffle cones) are completely used up.
-the number of the limiting reagent is the theoretical yield.
Percent Yield
-a measure of how well the reaction went.
-a comparison to what you actually got in the experiment to what you should have gotten (theo. yield.)
Equation:
Actual Yield/Theoretical Yield. x100

Example: 8/10=80% yield which means you attempted to make 10 ice cream cones but only had 8 waffle cones, so that is how many you could make in total.
Actual Yield
the measured amount of a product of a reaction
Can you determine how much of the excess reactant is left over in both grams and mL?-Need to do a third M2 M problem to find how much of the excess was used. -Use Theo. yield and convert to excess reagent. This is how you find out how much excess reagant was used. -Then subtract the used from what you started with.If given two amounts of reactants in both grams & volumes, can you determine which will be the limiting reagent; the reagent in excess; the theoretical yieldCan you write a balanced equation for a complete combustion reaction? Incomplete combustion? Can you ID the type of combustion based on Limiting reagents?Complete combustion reaction: Fuel + O2--> CO2 + H20 Incomplete: Fuel + O2--> CO2 + CO + C + H2O -The limiting reagent for incomplete combustion is Oxygen. (Excess is fuel) -The limiting reagent for complete combustion is fuel. (Excess is oxygen).