Stoichiometry Worksheet

 

Part 1

 

1. Use the balanced chemical reaction for the combustion of propane, C3H8 and dimensional analysis to answer the questions below.

C3H8  +  5 O2  ˆ 3 CO2   +   4 H2O

 

A) Write the equivalence statements based on the balanced chemical reaction.

 

a) ____________C3H8 = __________ O2                           ____________C3H8 = __________ CO2

 

____________C3H8 = __________ H2O

 

b) ____________O­2 = ___________ C3H8                        ____________O­2 = ___________ CO2

 

 ____________O­2 = ___________ H2O

 

c) How many molecules of carbon dioxide will be produced if 20 molecules of propane react?

 

 

 

d) How many molecules of oxygen react with 20 molecules of propane?

 

 

 

e) If 100 molecules of oxygen react, how many molecules of water will be produced?

 

 

 

f) If 3.75 E 23 molecules of oxygen react, how many molecules of carbon dioxide will be produced?

 

 

 

g) How many moles of carbon dioxide will be produced if 20.0 moles of oxygen react?

 

 

 

h) If 8.50 moles of water is produced by this reaction, how many moles of oxygen reacted?

 

 

 

2. Use the balanced chemical reaction for the combustion of propane, C3H8, to answer the questions below.

C3H8  +  5 O2  ˆ 3 CO2   +   4 H2O

 

A) A student conducts an experiment using the reaction above. When she burns 44.0 grams of propane, 160.0 grams of oxygen is consumed. 132 grams of carbon dioxide and 72 grams of water are produced. Does this data support the Conservation of Mass? How are these masses related to the coefficients in the balanced reaction? Use the masses given to support both of your answers.

 

 

 

 

 

 

 

B) Write the equivalence statements based on the balanced chemical reaction.

 

a) ____________C3H8 = __________ O2                           ____________C3H8 = __________ CO2

 

____________C3H8 = __________ H2O

 

b) ____________O­2 = ___________ C3H8                        ____________O­2 = ___________ CO2

 

 ____________O­2 = ___________ H2O

 

B) How many moles of O2 will react with 2.00 moles of propane?

 

 

 

 

 

C) How many moles of carbon dioxide will be produced if 2.00 grams of O2 react?

 

 

 

 

 

 

D) How many grams of propane react to produce 8.00 grams of water?

 

 

 

 

3.  Laughing gas, N2O can be turned into smog NO2 by heating the laughing gas in the presence of oxygen.

2N2O (g)             +             3O2 (g)                                    ˆ                              4NO2 (g)

 

A) 9.00 grams of laughing gas react. How many moles of oxygen react?

 

 

 

 

 

B) If 7.50 grams of oxygen react, how many grams of smog are produced?

 

 

 

 

 

4. The acid in your stomach that aids in breaking down proteins is called hydrochloric acid, HCl. Occasionally the glands that produce the HCl make more than is needed and you get those nasty sour burps. You can neutralize the excess acid by taking milk of magnesia. The active ingredient in milk of magnesia is Mg(OH)2. The chemical reaction is shown below.

 

2 HCl                    +              Mg(OH)2             ˆ           MgCl2                   +               2H2O

 

A) If you drink 2.00 grams of Mg(OH)2, how many moles of HCl are neutralized?

 

 

 

 

B) If your glands produced 8.33 x 1021 molecules, how many grams of Mg(OH)2 must you drink to neutralize all of this acid?

 

 

 

 

5. Consider the double replacement reaction below. The lead(II) idodide is a bright yellow insoluble substance. Prior to the 1960Õs it was used as a dye in yellow paint.  Lead poisoning could result if you eat the paint so is different dye is used in todayÕs paint.

Sodium iodide                    + lead (II) nitrate             ˆ           Sodium nitrate                   +               Lead (II) iodide

A) Write a balanced reaction.

 

 

B) If 10.0 grams of sodium iodide react, how many grams of lead (II) iodide are produced.

 

 

 

C) When a student completes this reaction she filters and dries the lead (II) iodide. The mass of the yellow solid is 8.67 grams. What is the actual, theoretical and percent yield?
Part 3 Limiting Reactants

 

 

 

6. Thionyl chloride, SOCl2, is used as a powerful drying agent. The thionyl chloride reacts with water as shown by the reaction below.

 

SOCl2   (l)             +               H2O (l)                   ˆ SO2 (g)         +               2HCl  (g)

A) 35.0 grams of thionyl chloride is placed in a glass containing 500.0 grams of water. Which substance is the limiting reactant? Briefly explain your answer.

 

 

 

 

 

 

 

 

B) 35.0 grams of thionyl chloride is placed in a glass containing 500.0 grams of water. How many grams of water will react? How many grams of thionyl chloride will react?

 

 

 

 

 

 

 

C) 35.0 grams of thionyl chloride is placed in a glass containing 500.0 grams of water. After the reaction is complete how many grams of water will remain unreacted? How many grams of the thionyl chloride will remain unreacted?

 

 

 

 

 

 

D) 35.0 grams of thionyl chloride is placed in a glass 500 grams of water. How many HCl molecules will be produced by this reaction?

 

 

 

 

7. For each of the unbalanced reactions below5.00 grams of each reactant is mixed together.

A) Balance the reaction.

B) Determine which substance is the limiting reactant.

C) Determine the mass of the excess substance that remains after the reaction is complete.

D) Find the mass of one of the products made by the reaction.

System #1

CaC2   +               H2O        ˆ            Ca(OH)2               +               C2H2

First balance the reaction.

Which substance is the limiting reactant? Briefly explain.

 

 

 

 

 

 

Determine the mass of excess that remains unreacted. Show your work.

 

 

 

 

 

What mass of Ca(OH)2 is produced in the reaction? Show your work.

 

 

 

 

 

System #2

Na2B4O7                +               H2SO4                     +               H2O  ˆ                H3BO3                    +               Na2SO4 

First balance the reaction.

Which substance is the limiting reactant? Briefly explain.

 

 

 

 

 

 

Determine the mass of excess that remains unreacted. Show your work.

 

 

 

 

 

What mass of H3BO3 is produced in the reaction? Show your work.