CP Chapter 12 Stoichiometry
What is Stoichiometry? ( STOY-KEE-AHM-EH-TREE)
•
Stoichiometry is the part of chemistry that studies amounts of reactants and products that are
involved in reactions.
•
Chemists use a ___________________ chemical __________________ as a basis to calculate
how much reactant is _____________ or product is _____________ in a reaction.
•
A balanced chemical equation can be interpreted in terms of different quantities, including
number of ____________, ____________, or ______________.
•
In a balanced chemical equation, the ________________________ in an equation represents
not only numbers of individual _________________ but also numbers of ______________.
•
The basis for stoichiometry is the law of conservation of mass, which states the mass of the
reactants will ____________________ the mass of the products.
What Do the Coefficients Mean?
Balance the equation.
____N2
•
+
____H2 à ____NH3
This equation can be looked at with ________ molecule of N2 reacts with __________ molecules
of H2 to produce two ________________ of NH3.
Or
•
This equation can be looked at as one mole of N2 reacts with three ____________ of H2 to
produce _________ moles of NH3.
Mole Ratio
•
A mole ratio is a _______________ factor derived from the ______________ of a balanced
chemical equation interpreted in terms of ______________.
Balance the equation and write all six mole ratios.
____Fe +
____O2 à
____Fe2O3
Balance the equation and write all six mole ratios.
____Al
+
____Br2 à
____AlBr3
1 Mole to Mole
How many moles of CO2 will be produced by the complete reaction of 2.00 mol of glucose (C6H12O6)?
____C6H12O6 +
____O2
à
____CO2 +
____H2O
How many moles of ammonia (NH3) can be produced from 8.50 mol of hydrogen reacting with nitrogen?
____H2(g)
+
____N2(g) à
____NH3(g)
How many moles of aluminum are needed to form 4.73 mol of Al2O3?
____Al(s) + ____O2(g) à
____Al2O3(s)
2 Mole to Mass
What mass of hydrogen can be produced by reacting 6.000 mol of Al with HCl?
____Al +
____HCl à
____AlCl3 +
____H2
What mass of AlCl3 can be produced by the reaction of 4.00 mol of HCl with Al?
Mass to Mole
How many moles of water can be produced by burning 325 g of octane (C8H18)?
____C8H18 + ____O2 à> ____CO2 + ____H2O
How many moles of CO2 can be produced by using up 145 g of oxygen?
3 Mass to Mass
What mass of carbon dioxide is produced by the complete combustion of 100.0 g of pentane (C5H12)?
____C5H12 +
____O2 à
____CO2 +
____H2O
How many grams of HNO3 are required to produce 8.75 g of dinitrogen monoxide (N2O) according to
the following equation?
____Zn + ____HNO3 à ____Zn(NO3)2 + ____N2O + ____H2O
How many grams of NH3 are produced by the reaction of 5.40 g of hydrogen with excess nitrogen?
____N2(g) + ____H2(g) à ____NH3(g)
4 Limiting Reactant (Limiting Reagent)
•
Limiting reactant or reagent - The ______________ that is totally used up during the chemical
reaction, ______________ the amount of ____________ produced.
•
Excess reactant or reagent – The _____________ present in a quantity that is ___________than what is needed to react with the __________________ reactant. The
excess reactant ___________ after the limiting reactant has been used up.
•
Note: The limiting reactant is not necessarily the substance that has the lower amount of
reactant. The limiting reactant is the one that will produce the least amount of product.
What is the limiting reactant? ___________________________________________
What are the excess reactants?__________________________________________
5 How many grams of silver bromide (AgBr) can be formed when solutions containing 50.0 g of MgBr2 and
100.0g of AgNO3 are mixed together? What is the limiting reactant? What is in excess?
____MgBr2 + ____AgNO3 à ____AgBr + ____Mg(NO3)2
How many grams of hydrogen chloride can be produced from 1.00 g of hydrogen and 55.0 g of chlorine?
What is the limiting reactant? What is in excess?
____H2 + ____Cl2 à____HCl
6 How many grams of barium sulfate (BaSO4) will be formed from 200.0 g of barium nitrate (Ba(NO3)2)
and 150.0 g of sodium sulfate (Na2SO4)? What is the limiting reactant? What is in excess?
____Ba(NO3)2 + ____Na2SO4 à ____BaSO4 + ____NaNO3
Percent Yield
• Theoretical yield is the __________________________ amount of product that can be
produced from a given amount of __________________________. Theoretical yield is
calculated using stoichiometry.
•
Actual yield is the amount of product actually produced when the chemical reaction is carried out
in an _________________________.
•
Percent yield is a comparison of the actual and percent yield. In general, the higher the percent
yield, the better the results are for the experiment.
Percent Yield =
_______________________________________
7 Determine the theoretical yield of Ag2CrO4 if 0.500 g of AgNO3 is used to react with K2CrO4. Also, if
0.455 g of Ag2CrO4 is obtained from an experiment, calculate the percent yield.
____AgNO3(aq) + ____K2CrO4(aq) à ____Ag2CrO4(s) + ____KNO3(aq)
CCl4 was prepared by reacting 100.0 g of CS2 and 100.0 g Cl2. Calculate the theoretical yield and
percent yield if 65.0 g of CCl4 was obtained from the reaction.
____CS2 + ____Cl2 à ____CCl4 + ____S2Cl2
8 Silver bromide (AgBr) was prepared by reacting 200.0g of magnesium bromide and 100.0 g of silver
nitrate. Calculate the theoretical and percent yield if 100.0 g of silver bromide was obtained from the
reaction
____MgBr2 +____AgNO3 à ____Mg(NO3)2 + ____AgBr
CP Chapter 12 Study Guide (WRITE YOUR ANSWERS ON A SEPARATE SHEET OF PAPER OR YOU WILL NOT BE GIVEN CREDIT.) 1.
2.
3.
What is conserved in a chemical reaction – moles, liters, mass, atoms, or molecules? (The answer could be more than one thing). In a chemical reaction what can you say about the mass of the products in relation to the mass of the reactants? What is the ratio of CO to CO2 in 2CO + O2 à 2CO2? 4.
How many moles of Al are needed to react completely with 2.4 mol of FeO? 2Al + 3FeO à 3Fe + Al2O3 5.
How many moles of oxygen react with 3.4 mol of Fe in the rusting reaction? 4Fe + 3O2 à 2Fe2O3 6.
How many grams of Fe2O3 are formed when 17.6 g of Fe reacts completely with oxygen? 4Fe + 3O2 à 2Fe2O3 7.
8.
9.
How many moles of H3PO4 are produced when 67.0 g of P4O10 reacts completely to form H3PO4? P4O10 +6H2O à 4H3PO4 How many grams of H3PO4 are produced when 15.0 moles of water react with an excess of P4O10? Use the equation in #7. What is the maximum number of grams of PH3 that can be formed when 7.5 g of P4 reacts with 5.8 g of H2 to form PH3? P4 + 6H2 à 4PH3 10. How many moles of Cu can be obtained from 3.5 mol of Al and 15 mol of CuSO4? What is the limiting reactant? Al + 3CuSO4 à Al2(SO4)3 + 3Cu 11. What is the percent yield of the decomposition reaction if 19.9 g Pb(NO3)2 are heated to give 7.5 g of PbO? 2Pb(NO3)2 à 2PbO + 4NO2 + O2 12. In a particular reaction between copper metal and silver nitrate, the theoretical yield was 40.0 g Ag. The experiment produced 38.1 g Ag. What is the percent yield of silver in this reaction? Cu + 2AgNO3 à Cu(NO3)2 + 2Ag 9