CHM1032C Grading Outline

Chapter 6 Chemical Reactions: Moles and Mass Relationships

A._____(02) Molecular Mass Calculation-Section6.1 Answers a

B._____(02) Mole Calculations I-Sections 6.2 Answers bcd

B1._____(02) Mole Calculations II-Sections  6.2 Answers bcd

C._____(02) Percentage Composition Calculation-Lecture Answers bcd

D._____(02) Empirical Formula Calc. from % Comp-Lecture Answers bcd

D1._____(02) Empirical Formula Calc. from Lab Data-Lecture Answers bcd

I.______(02) Mole-Mole Problems Section 6.3  Answers ij

J._____ (03) Mass-Mass Stoichiometric Problems-Section 6.4 Answers ij

K._____(03) Excess/Limiting Reagent ProblemsSection 6.5 -Answers kl

L._____(02) Percent Yield-Section 6.5 Answers

______(14)  Chapter 6 Total

                                                                                    

Chapter 6: Chemical Reactions:  Mole and Mass Relationships Table Contents
6.1 The Mole and Avogadro’s Number M-5B
6.2 Gram—Mole ConversionsM-5A/B1
6.3 Mole Relationships and Chemical Equations M-5I
6.4 Mass Relationships and Chemical EquationsM-5J
6.5 Limiting Reagent and Percent Yield M-5K

Chapters 3 through 7 Concept Map:


Module Five-Part A: Molecular Mass Calculation    2 points

1 mole of atoms = 6.023 x 1023 atoms. See “What is a mole?” Lab Analogies.


The atomic mass of any substance expressed in grams is the molar mass (MM) of that substance.

•          The atomic mass of carbon is 12.01 amu per atom.

•          Therefore, the molar mass of carbon is 12.01 g/mol  .

•          Since nitrogen occurs naturally as a diatomic, N2, the molar mass of nitrogen gas is two times          14.01 g or 28.02 g/mol.

Calculating Molar Mass

•          The molar mass of a substance is the sum of the molar masses of each element.

•          What is the molar mass of copper(II) nitrite, Cu(NO2)2?

•          The sum of the atomic masses is as follows:

                63.55 + 2(14.01 + 16.00 + 16.00) =

                63.55 + 2(46.01) = 155.57 amu per molecule

•          The molar mass for Cu(NO2)2 is 155.57 g/mol.

Molar Mass Connects  Moles to Grams & Vice versa:

 

Module Five-Part A: Molecular Mass Calculation    2 points

Homework #1:

Using a periodic chart calculate the molar mass of the following:
1. Calculate the molecular mass of Acetic Acid, HC2H3O2.

 

 

 

 

 

2. Calculate the formula unit mass of Ammonium Chromate, (NH4)2CrO4 .

 

 

 

 

 

 

3. Calculate the molecular mass of glucose,  C6H12O6.

 

 

 

 

 

 

 

Reference:

McMurry Section 6.2 Try problems: 6.23, 6.24, 6.27, 6.30, 6.31, 6.32, 6.33, 6.34, 6.35

Corwin Section 8.3 Additional Problems: Corwin #13-#16 Pages 244-245

Hein: Section 7.2: Example 7.7; 7.8 End of Chapter #1-#2 Page 139

Interactive Online Chem-i-Calc(Molar Mass & % Composition):

http://people.emich.edu/bramsay1/ccc-release/chem.html

 

 

Chapter 6 Sections 6.3-6.4-Lecture


 

 

From Another Text:

Chapter 6: Part I  Mole-Mole Stoichiometry   2 points

Homework #1: Tungsten occurs in the important mineral sheelite (Calcium tungstate), which is converted to tungstic acid.  Tungsten is then extracted from tungstic acid by the following (unbalanced) reaction:    

      H2   +       H2WO4      à        W        +        H2O   (Unbalanced)

How moles of hydrogen is needed to prepare 6 moles of elemental tungsten?

 

 

 

 

 

 

 

Homework #2: Phosphoric acid can be made by the following (unbalanced) reaction:

 H2O       +        P4O10     à              H3PO4         (unbalanced)

 

How many moles of Phosphoric acid can be prepared from the combination of 5 moles of Tetraphosphorus decoxide with excess water?      

 

 

 

 

 

 

References:

See McMurry: Section 6.3-6.4; See Worked Example 6.5;  Try Problem6.8 page 166

Try End of Chapter: Problems 6.39, 6.40

 

See Hein Worked Examples:  9.2-9.5 pages 170-173
Try Practice 9.2 and 9.3 page 173
Also try Problems 9-10-11-12 page 184

 

Corwin 7th Reference: Section 9.1-9.2
Corwin 1025: see worked Examples 9.2 page 253
additional Suggested Problems: Page 273-4 #7-#12

Chapter 6 Section J: Mass-Mass Stoichiometry  3 Points

Use this concept map for Part J Mass-Mass Problems:

 

Step 1:

A Mass-Mass Worked Example From Another book:

Using all three steps:

The Solution to:   __?____g Hg = 1.25g 1.25 g HgO

 

 

 

 

Another Mass-Mass Worked Example from Another book

 

 

 

 

 

Still Another Worked Example from Another book:

From book to book, the three steps are illustrated:

 

 

 

 

 

Chapter 6 Section J: Mass-Mass Stoichiometry  3 Points

Homework #3: Toluene and nitric acid are used in the production of trinitrotoluene (TNT), an explosive:

C7H8      +   HNO3       à      C7H5N3O6      +     H2O      (Unbalanced)

Calculate the mass of TNT that can be made from 192 g of C7H8 (toluene).
(You must use dimensional analysis to show your work!)

 

 

 

 

 

 

 

 

 

Homework #4: What mass of carbon dioxide is produced from the combustion of 176 grams of propane gas ,  C3H8 , in excess oxygen gas,  O2.
 Water is the only other product.
(You must use dimensional analysis to show your work!)

Write the Balanced Reaction:

 

 

 

 

 

 

 

 

 

Homework #5:

  1. What mass of carbon dioxide is produced from the combustion of 456 grams of gasoline ,  C8H18 , (2,2,4 Trimethyl Pentane)in excess oxygen gas,  O2.  Water is the only other product.
    (You must use dimensional analysis to show your work!)

Write the Balanced Reaction:

 

 

 

 

 

 

Engine knocking is an unwanted process that can occur during combustion in internal combustion engines. Graham Edgar in 1926 added different amounts of n-heptane C7H14)and 2,2,4-trimethylpentane to gasoline, and discovered that the knocking stopped when 2,2,4-trimethylpentane was added. This was the origin of the octane rating scale.[5] Test motors, using 2,2,4-trimethylpentane gave a certain performance which was standardized as 100 octane. The same test motors, run in the same fashion, using heptane, gave a performance which was standardized as 0 octane. All other compounds and blends of compounds then were graded against these two standards and assigned octane numbers.

Gasoline Molecule
2,2,4 Trimethyl Pentane

  1. Prove the quotation using dimensional analysis that burning one gallon of gasoline releases 18.7 tons of Carbon dioxide to the environment in a gasoline powered automobile. (Hint: There are 4 quarts = 1 gallon; 946 mL = 1 quart;
    454 grams = 1 pound; 2000 pounds = 1 ton)

 

 

 

 

 

 

  1. How many grams of oxygen gas will be the minimum requirement to completely combust the 456 grams of gasoline (just over a pound)?

 

 

 

 

 

 

 

 

  1. How many grams of water gas will exhaust out the tail pipe when the 456 grams of gasoline is combusted?

 

 

 

 

 

 

 

References:

McMurry:
See Worked examples 6.6 and 6.7 page 168Try Problem 6.10 page 169.
Also try end of chapter problems: 6.39 to 6.51 pages 175-176

See Hein Worked Examples  9.8-9.9 pages 174-175
Try Practice 9.6 and 9.7 page 176
Also try End of Capter Problems 13-18 page 184

see Corwin worked Examples 9.4 p256 and 9.5 p257
Try end of Chapter additional Suggested Corwin Problems: Page 274 #19-#27

 

Part K Excess-Limiting Reagent Problem    3 points

 

Sample Limiting Reagent Problem (Chapter 6 Part K)

 

 

 

 

 

 

Some books teach you to determine which reagent is the limit first, then do the standard gram-gram problem

 Either works, but I prefer the method above (working two separate
gram-gram problems and which produces the lowest number that is the correct sequence and answer.

Reference:
McMurry: Chapter 6 Section 6.5
See Worked Examples 6.9, 6.10, and 6.11 which also includes Percent yield (Chapter 6 Part L) pages 170-171; Try Problems 6.12, 6.13, and 6.14 page 171

Corwin:  Review Sections 9.7 and 9.8
see worked Examples 9.10 p267
additional Suggested Problems: p276 #59-#74

 

Hein:  Chapter 9 Section 9.5
see worked examples 9.11, 9.12, 9.13, 9.14 pages 178-181
Try problem 9.9 page 180; 9.10 page 181
End of chapter: Try