Stoichiometry Practice II
Honors Chemistry
Remember the steps to solving stoich problems:
1. Balance the equation
2. Write all given information under the compound or element
3. Write a ? and unit under compound you are trying to find
4. Set-up DA
a. Coefficients are to go from moles to moles
b. Molar mass is to go from grams to moles or moles to grams
Limiting and Excess Reagents:
1. Use the moles of both reagents and divide each reactant by the coefficient
of each. The smaller value is the limiting reagent.
2. From the moles of the limiting reagent, you can determine the mass being
produced. (coefficients and molar mass)
1. When 111.7 g of iron and 197.7 g of chlorine gas completely react, iron(III)
chloride, FeCl3(s), is formed.
a. Write the balanced equation for the reaction.
b. Calculate the number of moles of each reactant.
ANS: 2.000 mol Fe/2.788 mol Cl2
c. Which reactant is the limiting reagent?
d. How many grams of the product are formed?
ANS: 301.5 g
2. 75.0 mL of 0.100 M mercury(II) nitrate, Hg(NO3)2. are reacted with 125.0 mL
of 0.100 M sodium iodide, NaI(aq), then orange, solid mercury(II) iodide,
HgI2, and sodium nitrate, NaNO3(aq), are formed.
a. Write the balanced equation for the reaction.
b. Calculate the number of moles of each reactant.
ANS: 0.00750 mol Hg(NO3)2/0.0125 mol NaI
c. Determine the limiting reagent.
d. Calculate the mass in grams of the mercury(II) iodide.
ANS: 2.84 g
3. 125. mL of 0.200 M Silver nitrate is added to 50.0 mL of 1.00 M HCl. Solid
silver chloride is formed, along with aqueous HNO3.
a. Write the balanced equation for the reaction.
b. Calculate the number of moles of each reactant.
ANS: 0.0250 mol AgNO3/0.0500 mol HCl
c. Which reactant is the limiting reagent?
d. How many grams of the silver chloride is formed?
ANS: 3.58 g
e. In the lab, as student conducted the experiment and found out his
silver chloride massed out at 3.24 grams. What is the student’s
percent yield?
ANS: 90.5%
4. Use the following reaction to answer questions:
2AgNO3(aq) + CaCl2(aq)  2AgCl(s) + Ca(NO3)2(aq)
a. Nitro started with 100. mL and 0.500 M of silver nitrate and mixed
with 150. mL of 0.250 M of calcium chloride, calculate the number of
moles of each reactant.
ANS: 0.0500 mol AgNO3 and 0.0375 mol CaCl2
b. Using the moles of each reactant, calculate which reactant is limiting?
ANS: AgNO3
c. From the limiting reactant, how many grams of silver chloride are
produced?
ANS: 7.17 g AgCl
d. After completed the experiment, Nitro collected the solid silver
chloride and calculated the percent yield to be 86.9%. But like a bad
lab student Nitro forgot to write down his work and now can’t find the
mass of silver chloride he collected. How many grams of silver
chloride did Nitro collect?
ANS: 6.23 grams