AP Chemistry
Worksheet : Ch 3: Worksheet Introduction to Stoichiometry: obj. 25-28
Name :
Date :
A. Read pp. 114 - 123 and answer the following :
1. Describe the Haber process and state its importance(see p. 944).
2. _____________________ reagents limit or determine the amount of product that will be produced.
3. _____________________ reagents have a quantity which is more than enough to react with a limiting
reagent.
4. Identify the limiting reagent and the excess reagent for the following problem. You will need to write the
balanced equation first.
In the Haber process nitrogen and hydrogen are combined to form ammonia. If 2.30 grams of hydrogen are
combined with 20.00 grams of nitrogen which reactant is the limiting reactant and which is the excess
reactant? (Arbitrarily choose one reactant in its given unit and convert to the other reactant in its given unit,
i.e. g N2 to g H2 or g H2 to g N2 and compare to the given amount in the problem.)
5. Solid sodium metal reacts with oxygen gas to form solid sodium oxide. A reaction uses 2.50 moles of
sodium to react with 4.50 moles of oxygen gas. Identify the limiting reagent and determine how many
moles product are formed and how many moles of the excess reagent remains.
6. For the reaction above, how many grams of sodium oxide will be produced if 65.00 grams of sodium react
with 100.00 grams of oxygen? (Follow example 10 if needed).
7. ________________ yield is the calculated amount of product expected using the balanced equation.
8. ________________ yield is the amount of product produced when the reaction is carried out in the
laboratory.
9. ________________ yield is the ratio of the actual yield to the theoretical yield times 100 percent.
10. Solid sodium bicarbonate decomposes when heated to form solid sodium carbonate, water and carbon
dioxide gas. What is the percent yield in this reaction if 80.00 g of sodium bicarbonate produces 37.51 g of
sodium carbonate?
11. Lithium hydroxide combines with carbon dioxide to form lithium carbonate and water. If 500.0 g of
carbon dioxide are combined with an excess of lithium hydroxide and 812.2 g of lithium carbonate are
produced, what is the percent yield?
Other problems :
12. A pure sample of xenon fluoride has molecules with the formula XeFn. Given that 8.88 x 1018 molecules
weigh 3.06 x 10-3 g, determine n and the formula of the compound.
13. How many oxygen atoms are present in 2.20 ng of Mg3(PO3)2 ?
14. The Claus reaction generates elemental sulfur from hydrogen sulfide in the following steps :
2 H2S + 3 O2 
2 SO2 + 2 H2O
Fe2O3
SO2 + 2 H2S

3S + 2 H2O
How many grams of sulfur can be produced from 96.0 g of O2 ?
Answers : 6. H2 is limiting, N2 is excess 7. Na is limiting, 1.25 moles of Na2O are produced, 3.88 mol of O2
remain. 8. 87.61 g Na2O
10. 74.32% 11. 96.75% 12. n=4, XeF4 13. 3.44 x 1013 atoms O 14.
192 g