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OpenStax - Chemistry 2/e (Homework)

James Finch

Chemistry - College, section 1, Fall 2019

Instructor: Dr. Friendly

Current Score : 36 / 42

Due : Friday, February 1, 2030 12:00 EST

Last Saved : n/a Saving...  ()

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Question
Points
1 2 3 4 5 6 7 8 9
2/2 4/4 2/2 2/2 24/24 –/2 2/2 –/1 0/3
Total
36/42 (85.7%)

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    Cengage is proud to support the open source teaching community through our partnership with OpenStax. OpenStax's Chemistry is now enriched with WebAssign homework questions and student learning resources and is available as a low-cost option. The WebAssign content includes immediate student feedback, question links to appropriate sections of the eBook, as well as complete unabridged access to the textbook from a dynamic table of contents.

    Questions 1-5 are end-of-chapter questions from the OpenStax Chemistry textbook. These questions contain full algorithmic solutions for all question parts and showcase the variety of randomizations that WebAssign performs (shown in red) as well as various modes for student responses. These questions are denoted with "E" in the Question Browser.

    Questions 6-9 are from the exclusive WebAssign General Chemistry collection. This collection contains almost 1,400 questions that are correlated to OpenStax's Chemistry and feature feedback, step-by-step tutorials with Deep Help, and detailed algorithmic solutions. These questions are denoted with "WA" in the Question Browser. This demo assignment allows many submissions and allows you to try another version of the same question for practice wherever the problem has randomized values.

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1. 2/2 points  |  Previous Answers OSGenChem2 1.6.E.092. My Notes
Question Part
Points
Submissions Used
1 2
1/1 1/1
6/50 2/50
Total
2/2
 
Calculate these volumes.
(a)
What is the volume (in mL) of 13.4 g aluminum, density = 2.70 g/cm3?
WebAssign will check your answer for the correct number of significant figures. Correct: Your answer is correct. seenKey

4.96

 mL
(b)
What is the volume (in mL) of 38.533 g tungsten, density = 19.31 g/cm3?
WebAssign will check your answer for the correct number of significant figures. Correct: Your answer is correct. seenKey

1.995

 mL
†


Solution or Explanation
Process: Rearrange the known relationship for density to solve for the volume.
density = mass per unit of volume
volume = 
mass
density
(a)
volume = 
13.4 g
2.70 g/cm3
 = 4.9630 cm3 ≅ 4.96 mL
(b)
volume = 
38.533 g
19.31 g/cm3
 = 1.99549 cm3 ≅ 1.995 mL

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2. 4/4 points  |  Previous Answers OSGenChem2 1.1.E.005. My Notes
Question Part
Points
Submissions Used
1 2 3 4
1/1 1/1 1/1 1/1
2/50 1/50 1/50 1/50
Total
4/4
 
Identify each of the bold items as a part of either the macroscopic domain, the microscopic domain, or the symbolic domain of chemistry. For those in the symbolic domain, indicate whether they are symbols for a macroscopic or a microscopic feature. (Select all that apply.)
(a)
A certain molecule contains one C atom and one O atom.
Correct: Your answer is correct.

(b)
Aluminum wire has a density of about 3 g/cm3.
Correct: Your answer is correct.

(c)
The bottle contains 19 grams of Ti powder.
Correct: Your answer is correct.

(d)
A phosphorus molecule is composed of 4 phosphorus atoms.
Correct: Your answer is correct.

†


Solution or Explanation
(a)
A certain molecule contains one C atom and one O atom.
It is too small to be sensed directly: microscopic.
It uses specialized language: symbolic.
(b)
Aluminum wire has a density of about 3 g/cm3.
It is large enough to be sensed directly: macroscopic.
(c)
The bottle contains 19 grams of Ti powder.
It is large enough to be sensed directly: macroscopic.
It uses specialized language: symbolic.
(d)
A phosphorus molecule is composed of 4 phosphorus atoms.
It is too small to be sensed directly: microscopic.

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3. 2/2 points  |  Previous Answers OSGenChem2 11.2.E.011. My Notes
Question Part
Points
Submissions Used
1 2
1/1 1/1
2/50 3/50
Total
2/2
 
Consider the solutions presented.
(a)
Which of the following sketches best represents the ions in a solution of Fe(BrO3)3(aq)?
     Correct: Your answer is correct.
(b)
Write a balanced chemical equation showing the products of the dissolution of Fe(BrO3)3. (Include states-of-matter under the given conditions in your answer. Use the lowest possible whole number coefficients.)
Correct: Your answer is correct. seenKey

Fe(BrO_3)_3(s) --> Fe^3+(aq) + 3 BrO_3^-(aq)
Correct.
†


Solution or Explanation
(a)
Which of the following sketches best represents the ions in a solution of Fe(BrO3)3(aq)?
The given formula represents a strong electrolyte with 3 polyatomic anions for each 1 cation per formula unit. Strong electrolytes dissolve completely in water, so beaker z is the only depiction that fits the given formula.
(b)
Write a balanced chemical equation showing the products of the dissolution of Fe(BrO3)3.
Fe(BrO3)3(s) → Fe3+(aq) + 3 BrO3−(aq)

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4. 2/2 points  |  Previous Answers OSGenChem2 10.1.E.018. My Notes
Question Part
Points
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1 2
1/1 1/1
2/50 1/50
Total
2/2
 
Under certain conditions, molecules of formic acid, HCOOH, form "dimers," pairs of formic acid molecules held together by strong intermolecular attractions.
Draw a dimer of formic acid, showing how two HCOOH molecules are held together. (Use the "Any" bond type to indicate intermolecular attractions.)

Help

Marvin JS
Edit drawing
State the type of IMF that is responsible.
     Correct: Your answer is correct.
†

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5. 24/24 points  |  Previous Answers OSGenChem2 13.4.E.061. My Notes
Question Part
Points
Submissions Used
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1 1/1
1/50 1/50 1/50 1/50 2/50 2/50 2/50 2/50 2/50 2/50 1/50 1/50 1/50 1/50 1/50 1/50 1/50 1/50 1/50 1/50 1/50 1/50 1/50 1/50
Total
24/24
 
Please use the values in the resources listed below instead of the textbook values.
Complete the changes in concentrations (or pressure, if requested) for each of the following reactions.
(a)
Reaction 2 H2(g) + O2(g) equilibrium reaction arrow 2 H2O(g)
relative
change
−2x
Correct: Your answer is correct. -2x
−x
Correct: Your answer is correct. -x 		+2x
change in
concentration
(M) 		WebAssign will check your answer for the correct number of significant figures. Correct: Your answer is correct. seenKey

-1.90

 		WebAssign will check your answer for the correct number of significant figures. Correct: Your answer is correct. seenKey

-0.950

 		1.90
(b)
Reaction CS2(g) + 4 H2(g) equilibrium reaction arrow CH4(g) + 2 H2S(g)
relative
change 		+x
+4x
Correct: Your answer is correct. +4x
−x
Correct: Your answer is correct. -x
−2x
Correct: Your answer is correct. -2x
change in
concentration
(M) 		0.012 WebAssign will check your answer for the correct number of significant figures. Correct: Your answer is correct. seenKey

0.048

 		WebAssign will check your answer for the correct number of significant figures. Correct: Your answer is correct. seenKey

-0.012

 		WebAssign will check your answer for the correct number of significant figures. Correct: Your answer is correct. seenKey

-0.024
(c)
Reaction H2(g) + Cl2(g) equilibrium reaction arrow 2 HCl(g)
relative change +x
+x
Correct: Your answer is correct. +x
−2x
Correct: Your answer is correct. -2x
change in
pressure
(atm) 		1.30 WebAssign will check your answer for the correct number of significant figures. Correct: Your answer is correct. seenKey

1.30

 		WebAssign will check your answer for the correct number of significant figures. Correct: Your answer is correct. seenKey

-2.60
(d)
Reaction 2 NH3(g) + 2 O2(g) equilibrium reaction arrow N2O(g) + 3 H2O(g)
relative change
−23​x
Correct: Your answer is correct. -2x / 3
−23​x
Correct: Your answer is correct. -2x / 3
+13​x
Correct: Your answer is correct. +x / 3 		+x
change in
pressure
(torr) 		WebAssign will check your answer for the correct number of significant figures. Correct: Your answer is correct. seenKey

-43.6

 		WebAssign will check your answer for the correct number of significant figures. Correct: Your answer is correct. seenKey

-43.6

 		WebAssign will check your answer for the correct number of significant figures. Correct: Your answer is correct. seenKey

21.8

 		65.4
(e)
Reaction NH4HS(s) equilibrium reaction arrow NH3(g) + H2S(g)
relative change +x
+x
Correct: Your answer is correct. +x
change in
concentration
(M) 		9.5 ✕ 10−6 WebAssign will check your answer for the correct number of significant figures. Correct: Your answer is correct. seenKey

9.5e-06
(f)
Reaction Fe(s) + 5 CO(g) equilibrium reaction arrow Fe(CO)4(g)
relative change
−5x
Correct: Your answer is correct. -5x 		+x
change in
pressure
(atm) 		WebAssign will check your answer for the correct number of significant figures. Correct: Your answer is correct. seenKey

-0.065

 		0.013
†


Solution or Explanation
The relative change and change in concentration (or pressure) will have opposite signs on either side of the reaction. If the concentration/pressure of a reactant is increasing (positive relative change), any other reactants will also have a positive relative change, and the products will have a negative relative change. The opposite is true when the concentration/pressure of a product is increasing.
For each reaction, use the given relative change and the reaction coefficients to determine the other relative changes. Set the given change in concentration/pressure equal to the relative change to calculate the value of x. Substitute the value of x into the other relative changes to determine all changes in concentration/pressure.
(a)
Reaction 2 H2(g) + O2(g) equilibrium reaction arrow 2 H2O(g)
relative
change
−2x
−x
 		+2x
change in
concentration
(M) 		−1.90 −0.950 1.90
(b)
Reaction CS2(g) + 4 H2(g) equilibrium reaction arrow CH4(g) + 2 H2S(g)
relative
change 		+x
+4x
−x
−2x
change in
concentration
(M) 		0.012 0.048 −0.012 −0.024
(c)
Reaction H2(g) + Cl2(g) equilibrium reaction arrow 2 HCl(g)
relative change +x
+x
−2x
change in
pressure
(atm) 		1.30 1.30 −2.60
(d)
Reaction 2 NH3(g) + 2 O2(g) equilibrium reaction arrow N2O(g) + 3 H2O(g)
relative change
−2x
3
−2x
3
+x
3
 		+x
change in
pressure
(torr) 		−43.6 −43.6 21.8 65.4
(e)
Reaction NH4HS(s) equilibrium reaction arrow NH3(g) + H2S(g)
relative change +x
+x
change in
concentration
(M) 		9.5 ✕ 10−6 9.5 ✕ 10−6
(f)
Reaction Fe(s) + 5 CO(g) equilibrium reaction arrow Fe(CO)4(g)
relative change
−5x
 		+x
change in
pressure
(atm) 		−0.065 0.013

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6. –/2 points OSGenChem2 3.1.WA.012. My Notes
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–/1 –/1
0/50 0/50
Total
–/2
 
(a) How many moles of CO2 contain 2.95 ✕ 1024 molecules?
WebAssign will check your answer for the correct number of significant figures. mol CO2

(b) What number of moles is equivalent to 6.81 ✕ 1021 atoms of Hg?
WebAssign will check your answer for the correct number of significant figures. mol Hg

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7. 2/2 points  |  Previous Answers OSGenChem2 3.2.WA.013. My Notes
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1 2
1/1 1/1
1/50 1/50
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2/2
 
Write the molecular and empirical formulas for the compound with the following structural formula.

molecular formula:

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C6H12
C6H12

empirical formula:

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CH2
CH2



Solution or Explanation

  • Step 1 of 4

    Write the given structural formula of the compound.

  • Step 2 of 4

    Count the number of atoms of each element shown in the structural formula.
    There are 6 C atoms and 12 H atoms.

  • Step 3 of 4

    Write the molecular formula by writing the symbols for each element with a subscript indicating the number of atoms of that element determined in Step 2. Assume subscripts of "1" are understood; do not write "1" subscripts in the molecular formula.
    The six atoms of C are indicated by a subscript "6". The twelve atoms of H are indicated by a subscript "12".

    The molecular formula of the compound is the following.
    C6H12

  • Step 4 of 4

    Determine the empirical formula of the compound from its molecular formula. Assume subscripts of "1" are understood; do not write "1" subscripts in the empirical formula.
    The ratio between C and H atoms is 6:12. The smallest equivalent whole-number ratio is 1:2. Therefore, the empirical formula of the compound is the following.
    CH2

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8. –/1 points OSGenChem2 3.2.WA.014. My Notes
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Points
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1
–/1
0/50
Total
–/1
 
A compound has an empirical formula of C4H7O and a molar mass of 142 g/mol. What is the molecular formula?

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9. 0/3 points  |  Previous Answers OSGenChem2 3.2.WA.019. My Notes
Question Part
Points
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1 2 3
–/1 –/1 0/1
0/50 0/50 1/50
Total
0/3
 
A 0.5717 g sample of an unknown acid was titrated with NaOH and found to contain 5.047 ✕ 10−3 mol acid. Another sample of the substance was subjected to elemental analysis, where it was determined that the composition of the unknown material is 63.17% C, 8.81% H, and 28.02% O.
(a) What is the molar mass of the unknown acid?
WebAssign will check your answer for the correct number of significant figures. g/mol

(b) What is the empirical formula of the unknown acid?

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(c) What is the molecular formula of the unknown acid?

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afa
C6H10O2
Did you recall molar mass is grams per mole? Did you calculate the number of moles of acid using the titration data? Did you determine the empirical formula assuming 100 g of substance, and then divide the empirical molar mass by the empirical formula mass to determine the number of empirical formulas present in one molecule?

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