Reaction Stoichiometry Web Quest Remember when watching the video “Ring of Truth” earlier in the year by Phil Morrison he showed you two things

about atoms: atoms get together in whole number ratios and in unique geometric patterns. We have focused in on the

geometric patterns in our study of the VSEPR model. In this unit, reaction stoichiometry, we are going to refocus in on

the idea that atoms get together in whole number ratios. To do the math of this unit we are going to use three major

ideas you have learned previously: the factor label method for problem solving, the mole (formula stoichiometry) and

writing balanced chemical equations. To review the factor-label method and formula stoichiometry you are to do the

five factor-label method problems in the review questions section. The problems get progressively more difficult and

your answer for each must include showing your work and then show an answer that his circled for grading. This work

and answers are to be done on the report page found later in this document. Remember when you circle your final

answers ask yourself three questions: Does the answer make sense? Does your answer have the correct number of sig

figs? Does the answer make sense?

Review Questions-Days 1-2 (32 points)

1. The above speed limit sign is posted in Canada. What is the speed limit in miles per hour? (Remember like I said

before I will give you any metric to English conversion: 1.609 km = 1 mile)

2. The earthquake in Japan on May 14, 2011 may have shortened the length of a day by 1.8 μs according to NASA.

This upcoming summer break is 88 days long, how many microseconds will this be from the last day of school till

some of you are back in room 267 for AP Chemistry?

3. There is about 1.0 troy ounce of gold per 1,000 cell phones. How many atoms of gold are in a cell phone?

(Remember like I said before I will give you any metric to English conversion: 1.0 troy ounce = 31.1 g)

4. According to the Institute of Medicine a human should drink about 1.9 L of liquid water a day. If your body

vaporizes all that water through sweating what would be the volume of the water vapor in mL? You may make

two huge assumptions, ideal behavior by the water vapor and the water vapor is at the conditions of STP?

(HINTS: Density of water is a “simple number” and STP allows you to use 22.42 L of a gas, water vapor)

5. A 12 ounce can of Coke™ shown above contains 39 grams of fructose, C6H12O6.

a. How many molecules of fructose are in the can?

b. How many carbon atoms are in the can from the sugar? (Hint: the final answer is not 6!)

Balancing Chemical Equations-Day 3 (3 points)

To review balancing chemical equations try the following PhET simulations: Balancing Chemical Equations. You will have

to have JAVA to run this simulation. Click on Run Now, and then in the bottom left click on Keep. Then open the

program by clicking here.

Once you are at the screen below, you can practice balancing equations for the making of ammonia, the separation of

water and the combustion of methane. You can change the coefficients for the reactant(s) and product(s) by clicking the

up and down buttons and when you have the coefficients correct you will get a .

When you have gotten three smiley faces for each reaction click on the tab “Balancing Games.” You should try playing

time games at all three levels. You will not be graded on your time, but just for discussion in class, record your time for

each level. My times are below where you should record your times. See if you can beat my time!

Limiting Reactants-Days 4 and 5 (28 points)

In reaction stoichiometry one of the more difficult concepts are problems called “limiting reactants.” Before trying the

real chemistry of this and the real math of these problems let us look at it from a conceptual standpoint and in context

of sandwich building by using the PhET simulation “Reactants, Products and Leftovers” You will have to have JAVA to

run this simulation. Click on Run Now, and then in the bottom left click on Keep. (This is just like you did for the last

simulation.) Then open the program by clicking in the same spot.

When you get to the screen shown below you are try the following steps. Set the sandwich to be made by changing the

slices of bread to two and the slices of cheese to one by clicking on the up arrow before each.

With this setting for “the sandwich” change the number of slices for both bread and cheese below and watch what

happens to the products being made.

1. Notice that if you don’t have the “right number” of each reactant some of the “reactant(s)” will be left over.

a. What is the number of products and leftovers if you select five for both the slices of bread and cheese at

the bottom of the simulation?

b. How must you change the number of reactant(s) so there are no leftovers without reducing the number

of sandwiches being made? How many sandwiches did you make now?

2. Push reset all. Mr. Morrow likes two slices of cheese on his sandwich. So change the settings at the top to look

like what is shown above.

a. What is the number of products and leftovers if you select five for both the slices of bread and cheese at

the bottom of the simulation?

b. How must you change the number of reactant(s) so there are no leftovers without reducing the number

of sandwiches being made? How many sandwiches did you make now?

3. You have 3 friends who have come to your house and they want a sandwich with three slices of bread and two

slices of meat and cheese. To make a sandwich for each friend, how many slices of bread and cheese will you

need to make a sandwich for each friend? (Hint: click on this tab!)

Okay enough sandwich building. Lets try and put what you have learned though into some “real reactions”

4. Notice that if you don’t have the “right number” of each reactant some of the “reactant(s)” will be left over.

a. What is the number of water molecules made and leftovers if you select five for both the number of

hydrogen and oxygen molecules at the bottom of the simulation?

b. How must you change the number of reactant(s) so there are no leftovers without reducing the number

of water molecules being made? How many water molecules did you make

5. Click on the tab “make ammonia.” If you want to make 6 molecules of ammonia how much of each reactant do

you need?

6. Click on the tab “combustion methane.” Start with ten molecules of each reactant .

a. What are the numbers of each of the products and who is left over and by how much?

b. If you limit the amount of oxygen in the real world (aka your Bunsen burner) how does this actually

change the reaction in terms of the products?

7. You should try playing time games at all three levels. You will not be graded on this, but just for discussion in

class, record your time for each level. My times are below where you should record your times. See if you can

beat my time!

Reaction Stoichiometry Worksheet –Days 6-9 (52 points)

The ten stoichiometry problems all have answers shown in ( ) at the end of each question. These answers are given so you can check

to see of you have done the problem correctly and not just write down the answer. To receive credit you must show work for each

problem. Showing work includes showing the” four steps” to solve a reaction stoichiometry problem as shown to you and discussed

in class. Sometimes you don’t need all four steps and sometimes you need to go beyond the four steps, but each problem has some

or all the basic four steps. The point value for each problem has been indicated on the answer page.

1. How many moles of oxygen gas and potassium chloride may be produced from the decomposition of 3.6 moles of potassium chlorate? (5.4 mol of oxygen, 3.6 mol of potassium chloride)

2. How many moles of chloric acid can be produced from 7.2 g of ClO2 according to the reaction, 6 ClO2 + 3 H2O 5 HClO3 + HCl (0.089 mol HClO3)

3. White phosphorus (P4) is used in military incendiary devices because it ignites spontaneously in air. How many g of P4 will react with 25.0 g of O2 according to the balanced equation, P4 + 5 O2 P4O10 (19.4 g)

4. How many grams of ClF3 can be produced from 12.4 g of chlorine and 14.0 g of fluorine? Cl2 + 3 F2 2 ClF3

(22.7 g ClF3, if you got 32.4 g ClF3 then you have the wrong LR!) 5. Gallium and sulfur react to form Ga2S3. A 4.00 g sample of gallium is reacted with 3.00 g of sulfur. What mass of

what substance remains in excess (aka how much is left over)? 2 Ga + 3 S Ga2S3 (0.24 g S) 6. The reaction of 0.68 g of NH3 with excess O2 according to the following reaction as an actual yield of 0.98 g of

NO. What is the percent yield? 4 NH3 + 5 O2 4 NO + 6 H2O (82%) 7. Consider the reaction, C6H6 + Br2 C6H5Br + HBr, what is the percent yield of C6H5Br if 42.1 g of C6H6 react with

73.0 g of Br2 making an actual yield of C6H5Br is 63.6 g? (88.6%) 8. What volume, in mL, of 0.358 M HCl will react completely with 0.250 g of Al(OH)3? (26.8 mL) 9. A TUMS tablet contains 500.mg of calcium carbonate and neutralizes stomach acid (hydrochloric acid). How

many mL of carbon dioxide gas is produced during this reaction. You may assume STP conditions in your stomach although the temperature is much higher in the stomach and the volume of gas produced will be even higher than your calculated number. (112 mL)

10. BONUS!! A 0.3342 g iron ore sample is dissolved in acidic solution and all iron is present as Fe2+. Titration of the sample required 38.75 mL of 0.01710 M KMnO4 solution. What is the mass percent of iron in the iron ore? H+ + MnO4

- + 5 Fe2+ 5 Fe3+ + Mn2+ + 4 H2O (55.37%)

Reaction Stoichiometry Virtual Lab-Days 6-9 (35 points)

For this lab you are to watch the video to see the lab performed by your favorite chemistry teacher. The goal of this lab

is to determine the number of atoms of iron (assuming the steel in the nail is all iron) and the number of atoms of zinc

in a galvanized nail and to determine the percent by mass of each metal . The nail’s mass was measured on an analytical

balance and then placed into a beaker containing 3.0 M hydrochloric acid. When the reaction was finished (when no

more bubbling occurred) the nail was removed , rinsed with distilled water and then rinsed with acetone to dry the nail

quickly. The dry nail was then placed on an analytical balance to determine its mass. After watching the video (you

may want to do this more than once !) you are to do and answer the following question on your own notebook paper.

1. Write a statement of purpose for this lab.

2. Make a data table or tables to record your quantitative and qualitative observations.

3. Write a balanced equation for the reaction of the galvanized nail with the hydrochloric acid.

a. Determine the substance that undergoes oxidation and reduction. Explain!

4. Calculate the mass of zinc on the galvanized nail.

5. Determine the number of atoms of iron and zinc in the galvanized nail.

6. Determine the percent by mass of each metal in the galvanized nail.

7. A written conclusion statement.

8. For bonus points, explain why “drying with acetone” works in terms of intramolecular and intermolecular forces.

Name: _______________________________ Period: ________________

Virtual Lab: Galvanized Nail

Item Points/Out of

Question #1 /2

Question #2 /5

Question #3 /5

Question #4 /6

Question #5 /6

Question #6 /6

Question #7 /5

Question #8 /(8)

TOTAL /35

Reaction Stoichiometry Discovery Lab-Days 9-11 (100 points)

Lab 15 Stoichiometry Product Formation

Introduction

For this lab, you and your lab partners will use your knowledge of double replacement reactions, ion solubility

rules and stoichiometry to make and isolate 2.500 grams of an ionic compound of your choosing that is

insoluble in water. At the end of this lab you are expected to turn in the pure, dry product. How you

accomplish this is up to you, but you must have my OK for your reaction and procedures before

beginning.

Lab Discussion

Some things you and your lab partners should keep in mind:

You will have three days to do the lab and this includes all pre-lab preparation

You may not use a reaction already done in any lab this year

The chemical reaction you use must be unique to your class period

A list of available ionic compounds can be found in the lab inventory notebook

You must submit one lab report for your lab team

You must have in writing before beginning any lab procedure: o A statement of purpose o A balanced chemical equation (including states of matter) o A net ionic equation (including states of matter) o A stoichiometry problem (two) showing the calculated amount of each reagent needed to make 2.500

grams of your product o A set of bulleted procedures o A list of equipment and materials need o Material safety information appropriate to your chemicals that will be used

(HINT: Don’t expose nitrate containing compounds to heat.) o A data table to record all qualitative and quantitative observation

You may not use more grams than necessary of each reagent. o You must request the gram amount of each reagent needed

Make sure to put all waste in the designated waste containers.

Limit the amount of water you use, remember you need to turn a pure, but dry product

Wear eye protection at all times!

Have a calculation section showing the work to obtain any number not directly measured in lab including actual yield, theoretical yield and percent yield

A conclusion reporting your results and discussion of your percent yield and why it was not 100%

BONUS POINTS! o IF you could made 2,500 kilograms of your product what use(s) could you find for your product? o IF you could sell your product, how much would it cost you to make 2,500 kg of your product?

Check the lab grading protocol for any and all point values

Good luck and remember TO THINK!

Lab 15

Stoichiometry Product Formation

Lab Partner 1: _______________________________

Lab Partner 2: _______________________________

Lab Partner 3: _______________________________

Item Points/Out of

Lab Partner Names /1

Date Experiment Started /1

Title of Experiment /1

Appropriate Purpose /3

Unique Product /15

Balanced Chemical Equation /8

Net Ionic Equation /6

Stoichiometry Problem (x2) /12

Procedures /15

Equipment and Materials List /5

Material Safety /5

Data Table (with appropriate information) /8

Calculations /10

Conclusion (Statement of Results, sources of error and effects) /10

BONUS (“Use for your product and $$$) /(20)

Late (10% for first day: second day late no credit)

TOTAL /100

NAME: ____________________________________________ PERIOD: ________________

Reaction Stoichiometry Answer Pages

Review Questions (32 points)

1. (4 points)

2. (7 points)

3. (6 points)

4. (6 points)

5. Molecular Mass or Molar Mass of Fructose = ____________________

a. (5 points)

b. (4 points)

Balancing Chemical Equations (3 points)

YOUR TIMES

Level 1: _____________________; Level 2: _____________________; Level 3: _____________________

MR. M’s TIMES

Level 1: _____1:16 ____________; Level 2: ________2:31__________; Level 3: ________7:43_________

Limiting Reactants (28 points)

1. (5 points)

a.

b.

2. (6 points)

a.

b.

3. (3 points)

4. (4 points)

a.

b.

5. (2 points)

6. (5 points)

a.

b.

7. YOUR TIMES (3 points)

Level 1: _____________________; Level 2: _____________________; Level 3: _____________________

MR. M’s TIMES

Level 1: _____3:31 ____________; Level 2: ________2:57__________; Level 3: ________6:45_________

Reaction Stoichiometry Worksheet (52 points)

1. (4 points)

2. (4 points)

3. (5 points)

4. (7 points)

5. (7 points)

6. (5 points)

7. (7 points)

8. (5 points)

9. (8 points)

10. (6 points-EC)

NAME: ____________________________________________ PERIOD: ________________

Reaction Stoichiometry Rubric

Item Points/Out of

Review Questions /32

Balanced Chemical Equations (reported game times ) /3

Limiting Reactants (including reported game times) /28

Reaction Stoichiometry Worksheet /52

Virtual Lab: Galvanized Nail /35

Discovery Lab: Product Formation /100

TOTAL /250