the mole packet 4-5 - holy family catholic...

1

Chemistry

Name:__________________

Period:____

The Mole

Packet 4-5

Day In Class Work

1 Molar Mass

2 Mole Conversions

3 Stoichiometry

4 How many atoms of sugar are in a drink

5 Smores Lab

6 Chemical Reaction Lab

7 Writing and Balancing Equations

8 Balancing Equations

9 Equation Lab

10 Self Test

11 Test

12-14 Precipitate Lab

Outcomes Students will define a mole and Avogadro’s hypothesis

Students will calculate the molar mass of elements and compounds

Given the number of grams present in a compound students will calculate the number of moles

present.

Students will balance chemical equations.

Students will qualitatively observe chemical reactions to determine signs of a chemical reaction

2

Significant Figures Worksheet

How many significant figures are in each of the following numbers?

1) 5.40 ____ 6) 1.2 x 103 ____

2) 210 ____ 7) 0.00120 ____

3) 801.5 ____ 8) 0.0102 ____

4) 1,000 ____ 9) 9.010 x 10-6

____

5) 101.0100 ____ 10) 2,370.0 ____

11) Why are significant figures important when taking data in the laboratory?

12) Why are significant figures NOT important when solving problems in your math class?

13) Using two different instruments, I measured the length of my foot to be 27 centimeters and

27.00 centimeters. Explain the difference between these two measurements.

14) I can lift a 20 kilogram weight over my head ten times before I get tired. Write this

measurement to the correct number of significant figures.

3

Molar Mass Practice Worksheet

Determine the number of elements in each of the following compounds:

1) NaBr Na = 1 Br = 2 2) PbSO4

3) Ca(OH)2 4) Na3PO4

5) (NH4)2CO3 6) C6H12O6

7) Fe3(PO4)2 8) (NH4)2S

9) Zn(C2H3O2)2 10) AgF

Determine the molar mass of each of the following compounds

12) Cl2 13) KOH

14) BeCl2 15) FeCl3

16) BF3 17) CCl2F2

18) Mg(OH)2 19) UF6

20) SO2 21) H3PO4

22) (NH4)2SO4 23) CH3COOH

24) Pb(NO3)2 25) Ga2(SO3)3

4

Chemical Reactions

In this lab the signs of a chemical reaction will be investigated. Record all observations of the

reactants, reaction and products in the table below.

Reactants → Products

Lab Work Reactants Reactions Product

Place 3 mL of 0.002M

KSCN in a test tube and

add 3mL of 0.2M

Fe(NO3)3

Place 3 mL of 0.1M

FeSO4 in a test tube and

add 6 drops of 0.1M

KMnO4 Shake after each

drop

Place 5 mL of 6M HCl

in to a test tube. Gently

slide a marble chip into

the HCl

Place 5 mL of 6M

CH3COOH in a test

tube. Gently slide a

marble chip into the

CH3COOH

Place 10 drops of 0.1M

K2CrO4 in to a test tube

and then add a few drops

of 0.1M AgNO3

Place 3 mL of Pb(NO3)2

into a test tube and add

10 drops of NaI

Place 5 mL of distilled

water into a test tube.

Measure the temperature

and add 5-7 pieces of

NH4NO3 stir and

remeasure the

temperature

Place 5 mL of distilled

water into a test tube and

measure the

temperature. Add 10

drops of concentrated

HCl then remeasure the

temperature.

Four signs of a chemical reaction:

1. 2

3. 4.

5

Writing a chemical equation:

The formula of the reactants are placed to the left of the arrow.

The formula of the products are placed to the right of the arrow.

Reactants → Products The words react with, and, plus indicate the placement of a plus (+) sign

The words produce, yield and to form indicate the placement of an arrow

the concentration or amount of the substance is not part of the equation

Sample: Given that potassium hydroxide, KOH, reacts with sodium chloride, NaCl, to yield

potassium chloride, KCl, and sodium hydroxide, NaOH.

KOH + NaCl →KCl + NaOH

Write an equation for the following word problems.

1. Barium hydroxide, Ba(OH)2 reacts with carbon dioxide, CO2, to produce barium carbonate,

BaCO3, and water.

2. Chromium and 3M hydrochloric acid, HCl, yields hydrogen gas, H2, and chromium II chloride,

CrCl3.

3. Propane, C3H8, reacts with oxygen, O2, to form carbon dioxide and water.

4. When calcium hydroxide, Ca(OH)2 , reacts with hydrochloric acid, HCl, calcium chloride,

CaCl2, and water are formed.

5. Magnesium, Mg, metal burns in oxygen, O2 gas with a bright white light to make a white

powder called magnesium oxide, MgO2.

6. A solution of sodium iodide, NaI, is added to a solution of potassium nitrate, KNO3, to make a

potassium iodide, KI, precipitate and a sodium nitrate, NaNO3, solution.

7. Gaseous hydrogen, H2, and gaseous oxygen,O2, react explosively to form water, H2O, vapor.

6

In an equation the number of atoms of each element reacted must be equal to the number of atoms of

each element produced. At each station there are various numbers of models representing the

molecules/atoms if a given chemical reaction.

Correctly write out and balance each chemical equation.

Stations:

1.

2.

3.

4.

5.

6.

7.

8.

7

Chemical Equations and Stoichiometry

B A L A N C I N G E Q U A T I O N S

1. __ZnS + __HCl __ZnCl2 + __H2S

2. __HCl + __Cr __CrCl2 + __H2

3. __Al + __Fe3O4 __Al2O3 + __Fe

4. __H2 + __Br2 __HBr

5. __Na2S2O3 + __I2 __NaI + __Na2S4O6

6. __LaCl3 + __Na2CO3 __La2(CO3)3 + __NaCl

7. __NH4Cl + __Ba(OH)2 __BaCl2 + __NH3 + __H2O

8. __Ca(OH)2 + __H3PO4 __Ca3(PO4)2 + __H2O

9. __La2(CO3)3 + __H2SO4 __La2(SO4)3 + __H2O + __CO2

10. __Na2O + __(NH4)2SO4 __Na2SO4 + __H2O + __NH3

11. __C4H10 + __O2 __CO2 + __H2O

12. __C7H6O2 + __O2 __CO2 + __H2O

13. __P4O10 + __H2O __H3PO4

14. __FeS2 + __O2 __Fe2O3 + __SO2

15. __NH3 + __O2 __NO + __H2O

16. __Fe + __HCl __H2 + __FeCl2

17. __PbO2 + __HCl __H2O + __PbCl2 + __Cl2

18. __Fe2O3 + __H2SO4 __Fe2(SO4)3 + __H2O

19. __NO2 + __H2O __NO + __HNO3

20. __C2H6S + __O2 __CO2 + __H2O + __SO2

8

Writing and Balancing Equations in the Lab

Laboratory 1:

Place a scoop of PbO2 into the bottom of a small test tube. Heat for 30 seconds. Continue to heat

while taking a GLOWING splint and placing it in the mouth of the test tube. To make a glowing

splint light the splint in the burner and then blow it out so it only glows. A gas forms and reacts to the

glowing splint, the gas is O2 and the other product is Pb. Write and balance this chemical equation.

Disposal: Place the solid waste in the waste can. Place 3 mL of 6M HCl into the test tube and place it on the rack.

Was the test tube out at the end of the period.

Laboratory 2:

Obtain a piece of magnesium ribbon. Hold one end of the Mg ribbon with a forceps while igniting the

other end in a Bunsen burner. CAUTION: Do not look directly at the Mg while it is burning. The

Mg reacts with oxygen to form magnesium oxide, MgO. Write and balance this chemical equation.

Disposal: Place the product in the solid waste can.

Laboratory 3:

Fill a large test tube a quarter full with 6M HCl and place it on the rack. Drop a piece of zinc into the

acid. After the reaction begins, bring a FLAMMING splint to the mouth of the test tube. What

happens? _______________. A flaming splint is a test for hydrogen gas, H2. Knowing that the other

product is ZnCl2, write and balance this chemical equation.

Disposal: Pour the content of the test tube into the sink.

Laboratory 4:

Place 10 drops of 0.1M K2CrO4 in a small test tube, add a few drops of 0.1M AgNO3. Describe the

reaction that is taking place. ________________________________________. The two products are

KNO3 and Ag2CrO4. Write and balance this chemical equation.

Disposal: Pour the content of the test tube into the sink.

Laboratory 5:

Place CuSO4∙5H2O in a test tube to a depth of 2.5cm. Hold the test tube at an angle and heat until a

substance appears at the mouth of the test tube. What appeared?____________. The other product is

CuSO4. Write and balance this chemical equation.

Disposal: Allow the test tube to cool, add water to dissolve the product and pour the content of the test tube into the

sink.

9

Mole Conversions for the Same Chemical

Mole to Atoms or Molecules Atoms or Moelcules to Moles

X Moles 6.022E 23

atoms X Atoms 1 mole

1 mole X 6.022E 23

atoms of X

Moles to Grams Grams to Moles

X Moles Molar Mass X Grams 1 mole

1 mole X Molar Mass of X

Grams to Atoms or Molecules Atoms or Molecule to Grams

Given Grams 1 Mole 6.022E 23

Given Atoms 1 Mole Molar Mass

Molar Mass 1 Mole 6.022E 23

1 Mole

Mole Conversions from One Chemical to another Chemical

Moles to Moles

Given Moles Desired Moles from equation

Given mole from equation

Grams to Moles

Given Grams 1 Mole Desired Moles from Equation

Molar mass of Given Given Moles from Equation

Moles to Grams

Given Moles Desired Moles from equation Desired Molar Mass

Given Moles from Equation 1 Mole

Atoms/Molecules to Moles

Given Atoms/Molecules 1 Mole Desired Moles from Equation

6.022E 23

Given Moles from Equation

Grams to Grams

Given Grams 1 Mole Desired Moles from Equation Desired Molar Mass

Molar mass of Given Given Moles from Equation 1 Mole

10

Molecules and Compounds

M O L A R M A S S & % C O M P O S I T I O N

I. Molar Masses

Given a periodic table, you should be able to calculate the molecular mass (in u’s) or the molar mass

(in grams) for any element or compound.

Examples: (give answers to two decimal places)

H2SO4 Cl2 Ca(OH)2 HC2H3O2

CO2 N2O NaOCl Al2S3

II. Fraction and Percent Composition It is useful to determine how much of a compound’s mass is made up of each element. Water, H2O,

for example has a molar mass of 18.02 g. The H’s mass is 2(1.0079) = 2.02 g. The O’s mass is 16.00

g.

We can set up fractions for each element: H = 02.18

02.2= 0.112 = 11.2%. O =

02.18

00.16= 0.888 =

88.8%.

This is called the percent composition. The fraction composition is a good in-between step.

Determine the fraction and percent composition of each element below (answer to one decimal place):

1. H2SO4

2. Ca(OH)2

3. HC2H3O2

4. CO2

5. N2O

6. NaOCl

7. Al2S3

11

Molecules & Compounds

Mole Calculations - Difficulty Level 1

1 mole = 6.02 x 1023

molecules = 22.4 L (@ STP)

1. Calculate the mass of 1.58 moles CH4. [molar mass CH4 = 16.0 g/mol]

G: 1.58 moles CH4

D: ? g CH4

1.58 moles CH4 =

2. What volume will 7.29 moles of CO2 gas occupy at STP?

G: 7.29 moles CO2

D: ? L CO2

7.29 moles CO2 =

3. How many molecules are there in a 0.00583 mole sample of H2O?

G: 0.00583 moles H2O

D: ? molecules H2O

0.00583 moles H2O =

4. What mass of CO2 gas occupies a volume of 100. Liters at STP? [molar mass CO2 = 44.0 g/mol]

G: 100. Liters CO2

D: ? g CO2

100. Liters CO2 =

5. How many molecules are in a 35.0 gram sample of H2O? [molar mass H2O = 18.0 g/mol]

G: 35.0 g H2O

D: ? molecules H2O

35.0 g H2O =

6. What volume will 5.25 x 1022

molecules of CH4 occupy at STP?

G: 5.25 x 1022

molecules CH4

D: ? L

5.25 x 1022

molecules CH4 =

12



1 mole = 6.02 x 1023



G:

D:

=


G:

D:

=


G:

D:

=

4. What mass of CO2 gas occupies a volume of 395 Liters at STP? [molar mass CO2 = 44.0 g/mol]

G:

D:

=


G:

D:

=



G:

D:

=

13



1 mole = 6.02 x 1023



G:

D:


G:

D:


G:

D:

4. What mass of CO2 gas occupies a volume of 10.8 Liters at STP? [molar mass CO2 = 44.0 g/mol]

G:

D:


G:

D:



G:

D:

14

Mass-Mole Conversion Calculate the molecular mass for each of the following molecules:

1. KOH 2. N2O2 3. Cu2SO4 4. Sr3(PO4)2

Using Factor-Labeling, convert each of the following from grams to moles:

5. 15.0 g C2H6 6. 140.0 g NaOH

7. 27.2 g H2O 8. 45.7 g CaCO3

Using Factor-Labeling, convert moles to grams in each of the following:

9. 1.5 moles NH3 10. 0.65 moles H2SO4

Using Factor-Labeling, convert the following to moles:

11. 3.01 x 1023

atoms Na 12. 2.41 x 1024

molecules CO2

Using Factor-Labeling, convert the following to atoms or molecules:

13. 2.56 moles Ca 14. 0.75 moles AlCl3

15

Using Factor-Labeling, find the following:

15. the number of grams in 1.25 x 1025

molecules of aluminum oxide.

16. the number of molecules in 115 g nitrogen dioxide.

17. the number of atoms of barium in 68.2 g of barium phosphate.

18. How many molecules are present in 15.4 g of CO2?

19. a. What would be the mass of 16.9 moles of propane (C3H8)?

b. How many propane molecules would it contain?

20. How many grams are in 2.45 moles of NaCl?

21. How many atoms are in 56 grams a F?

22. How many Au atoms are there in a 2.3cm x 5.6cm x 12.7 cm block of gold?

(Density = 19.3g/mL)

16

How many atoms of sugar do you drink?

Gatorade Sodium Sugar (C6H12O6)

Grams

0.095g

39g

Moles

Atoms/ Molecules

Powerade Sodium Sugar (C6H12O6)

Grams

0.053g

15g

Moles

Atoms/ Molecules

Caffe Latte Sodium Sugar (C6H12O6)

Grams

0.174g

16g

Moles

Atoms/ Molecules

Mountain Dew Sodium Sugar (C6H12O6)

Grams

0.05g

31g

Moles

Atoms/ Molecules

Life Water Sodium Sugar (C6H12O6)

Grams

0.025g

13g

Moles

Atoms/ Molecules

Coke Sodium Sugar (C6H12O6)

Grams

0.055g

39g

Moles

Atoms/ Molecules

17

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 3 CO2 + 4 H2O

A) Write the ration between the following compounds.

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?

___ NaNO3 + ___ PbO ___ Pb(NO3)2 + ___ Na2O

___ AgI + ___ Fe2(CO3)3 ___ FeI3 + ___ Ag2CO3

18

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

oxygen.

2N2O (g) + 3O2 (g) 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?

3. 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 MgCl2 + 2H2O

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

4. Balance the following equation

____ NaOH + ____ H2SO4 ____ H2O + ____ Na2SO4

How many grams of sodium sulfate will be formed if you start with 200 grams of sodium hydroxide

and you have an excess of sulfuric acid?

5 Using the following equation:

____ Pb(SO4)2 + ____ LiNO3 ____ Pb(NO3)4 + ____ Li2SO4

How many grams of lithium nitrate will be needed to make 250 grams of lithium sulfate,

assuming that you have an adequate amount of lead (IV) sulfate to do the reaction?

19

Chemical Equations and Stoichiometry

S T O I C H I O M E T R Y P R O B L E M S

General Stoichiometry

Several brands of antacid tablets use aluminum hydroxide to neutralize excess acid.

Al(OH)3(s) + 3 HCl(aq) AlCl3(aq) + 3 H2O(l)

[Molar masses: 78.01 36.46 133.4 18.02]

What quantity of HCl, in grams, can a tablet with 0.750 g of Al(OH)3 consume? What quantity

of water is produced?

If 10.0 g of carbon is combined with an exact, stoichiometric amount of oxygen (26.6 g) to produce

carbon dioxide, what mass, in grams, of CO2 can be obtained? That is, what is the theoretical

yield of CO2? [Molar masses: C: 12.011 O2: 32.00 CO2: 44.01]

The equation for one of the reactions in the process of reducing iron ore to the metal is

Fe2O3(s) + 3 CO(g) 2 Fe(s) + 3 CO2(g)

[Molar masses: 159.7 28.01 55.85 44.01]

(a) What is the maximum mass of iron, in grams, that can be obtained from 454 g (1.00 lb) of

iron(III) oxide?

(b) What mass of CO is required to reduce the iron(III) oxide to iron metal?

Burning coal and oil in a power plant produces pollutants such as sulfur dioxide, SO2. The sulfur-

containing compound can be removed from other waste gases, however, by the following

reaction:

2 SO2(g) + 2 CaCO3(s) + O2(g) 2 CaSO4(s) + 2 CO2(g)

[Molar masses: 64.07 100.1 32.00 136.2 44.01]

(a) Name the compounds involved in the reaction.

(b) What mass of CaCO3 is required to remove 155 g of SO2?

(c) What mass of CaSO4 is formed when 155 g SO2 is consumed completely?

Your body deals with excess nitrogen by excreting it in the form of urea, NH2CONH2. The reaction

producing it is the combination of arginine (C6H14N4O2) with water to give urea and ornithine

(C5H12N2O2).

C6H14N4O2 + H2O NH2CONH2 + C5H12N2O2

[Molar masses: 174.2 18.02 60.06 132.2]

If you excrete 95 mg of urea, what quantity of arginine must have been used? What quantity of

ornithine must have been produced?

20

Limiting Reactants

The reaction of methane and water is one way to prepare hydrogen:

CH4(g) + H2O(g) CO(g) + 3 H2(g)

[Molar masses: 16.04 18.02 28.01 2.02]

If you begin with 995 g of CH4 and 2510 g of water, what is the maximum possible yield of H2?

Disulfur dichloride, S2Cl2, is used to vulcanize rubber. It can be made by treating molten sulfur with

gaseous chlorine:

S8(l) + 4 Cl2(g) 4 S2Cl2(l)

[Molar masses: 256.6 70.91 135.0]

Starting with a mixture of 32.0 g of sulfur and 71.0 g of Cl2, which is the limiting reactant? What

mass of S2Cl2 (in grams) can be produced? What mass of the excess reactant remains when the

limiting reactant is consumed?

Aspirin (C9H8O4) is produced by the reaction of salicylic acid (C7H6O3) and acetic anhydride (C4H6O3)

(page 163).

C7H6O3(s) + C4H6O3(l) C9H8O4(s) + CH3CO2H(aq)

[Molar masses: 138.1 102.1 180.1 60.05]

If you mix 100. g of each of the reactants, what is the maximum mass of aspirin that can be

obtained?

Percent Yield

Diborane, B2H6, is a valuable compound in the synthesis of new organic compounds. One of several

ways this born compound can be made is by the reaction

2 NaBH4(s) + I2(s) B2H6(g) + 2 NaI(s) + H2(g)

[Molar masses: 37.84 253.8 27.67 149.9 2.02]

Suppose you use 1.203 g of NaBH4 with an excess of iodine and obtain 0.295 g of B2H6. What is

the percent yield of B2H6?

Disulfur dichloride, which has a revolting smell, can be prepared by directly combining S8 and Cl2,

but it can also be made by the following reaction:

3 SCl2(l) + 4 NaF(s) SF4(g) + S2Cl2(l) + 4 NaCl(s)

[Molar masses: 103.0 41.99 108.1 135.0 58.46]

Assume you begin with 5.23 g of SCl2 and excess NaF. What is the theoretical yield of S2Cl2? If

only 1.19 g of S2Cl2 is obtained, what is the percent yield of the compound?

21

Excess Problems

1. Given the following equation: KCl + O2 → KClO3.

Given 74.33 grams of KCl are reacted with 65.22 grams of O2, which compound is limiting? How

many grams of KClO3 are produced?

2. Given the equation Pb + O2 → PbO2

Given 233.33 grams of Pb react with 39.90 grams of O2, which compound is limiting? Which

compound is in excess? How many grams of PbO2 are produced?

22

THE STOICHIOMETRY OF S’MORES

Introduction: In this laboratory experiment, you will explore the principles of stoichiometry by building

S’mores, the delicious, chocolate, marshmallow, and graham cracker treats.

Purpose:

To determine the limiting reactant in the synthesis of S’mores.

Materials:

Per Group:

1. 1 Chocolate bar

2. 6 Marshmallows

3. 5 Graham crackers

4. Paper plate

5. Napkins

6. Electronic balance

Procedures / Data: The following symbols will be used for each reactant.

C = chocolate square

M = marshmallow

G = graham cracker

1. Mass and record one of each reactant.

Chocolate square (the size you wish to use on each S’more): ________ g

Marshmallow: ________ g

Graham cracker (the size you wish to use on each S’more): ________ g

2. Perform a synthesis reaction, thus forming a S’more. Write the balanced equation for

the reaction below.

3. Cause the reaction to go to completion by forming as many of the products as you

possibly can. Mass and record ONE of the representative products.

S’more: ________ g

4. Count and record the number of products you were able to form. ________

Post-Lab Questions: 1. Is there a relationship between the mass of a S’more and the masses of the reactants used

to make it?

2. A limiting reactant is the material responsible for a reaction reaching completion. In the

reaction, what was the limiting reactant?

3. What reactants, if any, were in excess? Mass and record the total of each excess reactant.

Extension Questions: 1. How many S’mores could you make if you had started with 100g of each reactant?

2. What would be the limiting reactant?

3. How much of each excess reactant would result?

23

Self Test

A. Write an equation for the following reactions.

Iron III oxide, Fe2O3, reacts with carbon monoxide, CO, to produce iron and carbon dioxide.

Aluminum sulfate, Al2(SO4)3 reacts with calcium hydroxide, Ca(OH)2 to produce aluminum

hydroxide, Al(OH)3 and calcium sulfate, CaSO.

B Balance the following equations:

1) ___ N2 + ___ F2 ___ NF3

2) ___ C6H10 + ___ O2 ___ CO2 + ___ H2O

3) ___ HBr + ___ KHCO3 ___ H2O + ___ KBr + ___ CO2

4) ___ GaBr3 + ___ Na2SO3 ___ Ga2(SO3)3 + ___ NaBr

5) ___ SnO + ___ NF3 ___ SnF2 + ___ N2O3

Using the equation from problem 2 above, answer the following questions:

6) If I do this reaction with 35 grams of C6H10 how many grams of carbon dioxide will be formed?

7) If 2 moles of N2 reacts how many moles of NF3 are produced?

8) If 10.0g of SnO are used how many grams of SnF2 will be produced?

C. Calculate the molar mass of the following.

(NH4)2CO3 C6H12O6 Fe3(PO4)2

(NH4)2S Zn(C2H3O2)2 AgF

Cl2 KOH

25

PRODUCTION OF A PRECIPITATE

FROM SOLUTIONS OF

SODIUM IODIDE AND LEAD NITRATE

INTRODUCTION: How is the chemical formula for a substance determined? In this experiment you will react solutions of

lead nitrate, Pb(NO3)2 , and sodium iodide, NaI , of known concentration, 0.500 M. You will

observe the results when various volumes of these solutions are mixed. From the relative volumes of

the solutions used and their molar concentration, and from the masses of the precipitate formed, it will

be possible to determine the number of moles of the substances involved and the formula for the

precipitate.

Day 1

1. Wash and label two 50mL beakers for lead nitrate, Pb(NO3)2 , and sodium iodide, NaI.

2. Weigh the clean dry Pb(NO3)2 beaker and add exactly 0.93 grams of Pb(NO3)2.

3. Weigh the clean dry NaI beaker and add exactly 0.84 grams of NaI to the beaker.

4. Add exactly 15mL of distilled water to each beaker.

5. Stir the solutions until they dissolve.

6. Add one solution to the other and stir.

7. Weigh a piece of filter paper and record its mass in the Data Table.

8. Weigh a 100mL beaker and small watch glass together and record their mass in the Data

Table.

9. Stir the solution and pour the precipitate into the filter paper cone.

10. Rinse the beaker with a few milliliters of distilled water and pour it into the filter cone.

11. Repeat step 10 until all the precipitate is rinsed from the beaker.

12. When the filter paper has drained, pour a small amount of distilled water on the solid. The

water will rinse out any NaNO3.

13. Unfold the cone filter paper and lay it flat on the plastic lid found in the drawer. Allow it to

dry over night. Take a stirring rod to spread the yellow substance around on the paper. The

substance on the paper is PbI2. (Do not pour the liquid down the drain save it for tomorrow)

Day 2

1. Heat the filtrate with the watch glass on top until all the water has boiled off.

2. Weigh and record the beaker, watch glass, and NaNO3 mass when it is dry and cool in the

Data Table. 3. Weigh and record the filter paper and solid, PbI2 in the Data Table.

Data Table

Mass of filter paper Mass of empty beaker and watch glass

Mass of filter paper and solid, PbI2 Mass of beaker, watch glass, and NaNO3

Mass of PbI2 Mass of NaNO3

26

Calculations

1. Write and balance a chemical equation for the reaction that occurred.

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2. If 0.93 grams of Pb(NO3)2 are used in the reactions how many grams of PbI2 should be

produced? (grams-grams problem)

3. If 0.84 grams of NaI are used in the reactions how many grams of NaNO3 should be produced?

(grams-grams problem)

4. Using the data from the data table for as the experimental value and the answers from number 2

and 3 as the accepted value, determine the percent error for this lab.

Percent error = Experimental Value – Accepted Value X 100

Accepted Value

PbI2

NaNO3

the mole packet 4-5 - holy family catholic...

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