Name__________________________________ per ___ Note Taking Guide: Episode 802 Stoichiometry #2
http://www.gpb.org/chemistry-physics/chemistry/802
When nitrogen and hydrogen react, they form ammonia gas, NH3. If 56.0 grams of nitrogen are used up in the
reaction, how many grams of ammonia will be produced?
1st Step: Write a Balanced equation:
N2(g) + 3H2(g) → 2NH3(g)
nd
2 Step: Write the problem in question format:
? g NH3 = 56.0 g N2
3rd Step: Convert grams of N2 to MOLES:
56.0 g N2 ÷ 28.0 g/mol N2 = 2 moles N2
th
4 Step: Compare moles of N2 in the balanced equation to moles of NH3:
Given:
Found in balanced
equation
2 moles N2 = 1 mole N2
? moles NH3
2 moles NH3
Cross multiply & solve for ?
5th Step: Convert moles of NH3 to grams of NH3:
4 moles NH3 (17.0 g/mol NH3)
***This is what you did last week in your lab. (convert grams to moles, compare moles in balanced equation,
convert to grams)
1. Sodium metal reacts with oxygen gas to produce solid sodium oxide. How many grams of sodium must react
to produce 42.0 grams of sodium oxide? WRITE THE BALANCED EQUATION FIRST!!!! (Show your work!)
2. When 12.0 g of hydrogen reacts with oxygen, how many grams of water are produced? WRITE THE
BALANCED EQUATION FIRST!!!! (Show your work!)
3.
Actual Yield: amount of __________ produced when the __________ is performed in a __________
4. Theoretical Yield: amount of __________ expected to be __________ based on the _________ _________
and the amount of __________
5. Percent Yield (__________ yield / __________ yield) x 100%
6. What does a high percent yield mean?_______________________________________________
7. LAB Data:
Mass NaHCO3 (baking soda) _____________ grams
Mass of HCl (hydrochloric acid) & NaHCO3 (before rxn)_____________ grams
Mass of HCl (hydrochloric acid) & NaHCO3 (after rxn)_____________ grams
NaHCO3 + HCl → NaCl + CO2 + H2O
SHOW WORK
a. Actual yield of CO2 = _____________________ (from lab data)
b. Calculate theoretical yield from balanced equation: ? g CO2 = 0.23 g NaHCO3
c. % yield =
8. What is the % yield of carbon dioxide when 5.99 grams of propane, C3H8 are burned and 12.052 grams of
carbon dioxide is collected?
____C3H8 + ___ O2 → ____CO2 + ____H2O
9. Nitrogen and hydrogen react to form ammonia gas according to the following equation.
a. Balance: ___N2 + ___H2 → ___NH3
b. If 56.0 grams of nitrogen are used up by the reaction, how many grams of ammonia will be
produced?
c. How many grams of hydrogen must react if the reaction needs to produce 63.5 grams of ammonia?
10. Aluminum metal reacts with zinc chloride to produce zinc metal and aluminum chloride.
a. Balance: ___Al + ___ZnCl2 → ___Zn + ___AlCl3
b. A mass of 45.0 grams of aluminum will react with how many grams of zinc chloride?
c. What mass of aluminum chloride will be produced if 22.6 grams of zinc chloride are used up in the
reaction?
11. For the reaction whose balanced equation is as follows, find the number of grams of I2 that will be formed
when 300.0 g of bromine react. 2 KI + Br2 → 2 KBr + I2
12. For the reaction whose balanced equation is as follows, find the number of grams of sodium that must react
to produce 42.0 grams of sodium oxide. 4 Na + O2 → 2 Na2O
13. For the reaction whose balanced equation is as follows, find how many grams of zinc phosphate will be
produced by the reaction of 5.00 grams of ammonium phosphate. 3 ZnCl2 + 2 (NH4)3PO4  Zn3(PO4)2 + 6
NH4Cl
14. Chlorobenzene, C6H5Cl, is used in the production of chemicals such as aspirin and dyes. One way that
chlorobenzene is prepared is by reacting benzene, C6H6, with chlorine gas according to the following
BALANCED equation.
C6H6(l) + Cl2 (g) → C6H5Cl (s) + HCl (g)
a. What is the theoretical yield if 45.6 g of benzene react?
b. If the actual yield is 63.7 g of chlorobenzene, calculate the percent yield.
15. When carbon disulfide burns in the presence of oxygen, sulfur dioxide and carbon dioxide are produced
according to the following equation. CS2 (l) + 3 O2 (g) → CO2 (g) + 2 SO2 (g)
a. What is the percent yield of sulfur dioxide if the burning of 25.0 g of carbon disulfide produces 40.5 g
of sulfur dioxide?
b. What is the percent yield of carbon dioxide if 2.5 mol of oxygen react and 32.4 g of carbon dioxide
are produced?