10/11/2016
Homework 4 (Ch 4)
Homework 4 (Ch 4)
Due: 11:59pm on Wednesday, October 12, 2016
You will receive no credit for items you complete after the assignment is due. Grading Policy
Chapter 4 Question 1 ­ Algorithmic
Part A
Of the species below, only ________ is not an electrolyte.
ANSWER:
HCl
He
LiOH
KBr
RbNO3
Chapter 4 Question 1 ­ Bimodal
Part A
A strong electrolyte is one that ________ completely in solution.
ANSWER:
disappears
ionizes
reacts
associates
Chapter 4 Question 3 ­ Algorithmic
Part A
The total concentration of ions in a 0.5 M solution of HCl is ________.
ANSWER:
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Homework 4 (Ch 4)
0
1 M
1.25 M
0.5 M
0.375 M
Chapter 4 Question 4 ­ Bimodal
Part A
Which of the following are weak electrolytes? HNO3
HF
NH3
LiBr
ANSWER:
HNO3, HF, NH3, LiBr
HNO3, NH3, LiBr
HF, NH3
HNO3, LiBr
HF, LiBr
Chapter 4 Question 4 ­ True/False
Part A
The compound NH4Cl is a weak acid.
ANSWER:
True
False
Chapter 4 Question 5 ­ Algorithmic
Part A
Which of the following is soluble in water at 25∘ C?
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Homework 4 (Ch 4)
ANSWER:
Hg2 Cl2
AgCl
Ag2 S
PbCl2
AgNO3
Chapter 4 Question 5 ­ Bimodal
Part A
What are the spectator ions in the reaction between KOH (aq) and HNO3 (aq)?
ANSWER:
H+ and NO3­
K+ and NO3­
OH­ only
H+ and OH­
K+ and H+
Problem 4.7
Which of the following ions will always be a spectator ion in a precipitation reaction?
Part A
−
Cl
ANSWER:
always spectator ion
not always spectator ion
Part B
−
NO
3
ANSWER:
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Homework 4 (Ch 4)
always spectator ion
not always spectator ion
Part C
NH
+
4
ANSWER:
always spectator ion
not always spectator ion
Part D
S
2−
ANSWER:
always spectator ion
not always spectator ion
Part E
2−
SO
4
ANSWER:
always spectator ion
not always spectator ion
Problem 4.13
State whether each of the statements below is true or false. Justify your answer in each case.
Part A
Electrolyte solutions conduct electricity because electrons are moving through the solution.
ANSWER:
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Homework 4 (Ch 4)
True. Free electrons are produced when electricity passes through an electrolyte solution.
True. Electrons are present in electrolyte solutions but they only begin to move when electricity passes through
an electrolyte solution.
False. Electrolyte solutions conduct electricity because ions are moving through the solution.
False. Electrolyte solutions do not conduct electricity.
Part B
If you add a nonelectrolyte to an aqueous solution that already contains an electrolyte, the electrical conductivity will not
change.
ANSWER:
True. Because ions are mobile in solution, the added presence of uncharged molecules does not inhibit
conductivity.
True. Because nonelectrolyte molecules are charged by ions present in a solution.
False. Because electrical conductivity depends on the number of charge carriers present in a solution.
False. Because nonelectrolyte molecules shield ions in the solution from electric field.
Problem 4.14
State whether each of the statements below is true or false. Justify your answer in each case.
Part A
When chloroform, CHCl3 , is dissolved in water, a conducting solution results.
ANSWER:
True. Chloroform has a polar −CCl group which ionizes in aqueous solutions.
False. Chloroform is an organic compound, and does not dissociate in aqueous solutions.
Part B
When sodium acetate, CH3 COONa, dissolves in water, the solution is conducting and basic in nature.
ANSWER:
True. CH3 COONa is a strong electrolyte. When it dissolves in water, the molecules ionize to form Na+ and −
−
−
CH 3 COO ions. CH 3 COO hydrolizes to for OH which makes the solution basic.
False. Sodium acetate is a salt of a weak organic acid, and it is not ionizable.
Problem 4.16
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Homework 4 (Ch 4)
Part A
Would you expect that anions would be physically closer to the oxygen or to the hydrogens of water molecules that
surround it in solution?
ANSWER:
They will be attracted to and thus physically closer to the hydrogens.
They will be attracted to and thus physically closer to the oxygen.
Problem 4.22
Predict whether each of the following compounds is soluble in water.
Part A
AgI
ANSWER:
soluble in water
insoluble in water
Part B
Na2 CO3
ANSWER:
soluble in water
insoluble in water
Part C
BaCl2
ANSWER:
soluble in water
insoluble in water
Part D
Al(OH)
3
ANSWER:
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Homework 4 (Ch 4)
soluble in water
insoluble in water
Part E
Zn(CH 3 COO)
2
ANSWER:
soluble in water
insoluble in water
Problem 4.25
Which ions remain in solution, unreacted, after each of the following pairs of solutions is mixed?
Part A
potassium carbonate and magnesium sulfate
Express your answer as an ion. If there is more than one answer, separate them by a comma.
ANSWER:
Part B
lead nitrate and lithium sulfide
Express your answer as an ion. If there is more than one answer, separate them by a comma.
ANSWER:
Part C
ammonium phosphate and calcium chloride
Express your answer as an ion. If there is more than one answer, separate them by a comma.
ANSWER:
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Homework 4 (Ch 4)
Problem 4.26 with feedback
You may want to reference (
pages 128 ­ 132) Section 4.2 while completing this problem.
Part A
Write the balanced net ionic equation for the reaction that occurs in the following case:
Cr2 (SO4 ) (aq) + (NH 4 ) CO3 (aq)→
3
2
Express your answer as a balanced net ionic equation. Identify all of the phases in your answer.
ANSWER:
Part B
Identify the spectator ion or ions in this reaction.
Express your answer as an ion. If there is more than one answer, separate them by a comma.
ANSWER:
Part C
Write the balanced net ionic equation for the reaction that occurs in the following case:
Ba(NO3 ) (aq) + K2 SO4 (aq)→
2
Express your answer as a balanced net ionic equation. Identify all of the phases in your answer.
ANSWER:
Part D
Identify the spectator ion or ions in this reaction.
Express your answer as an ion. If there is more than one answer, separate them by a comma.
ANSWER:
Part E
Write the balanced net ionic equation for the reaction that occurs in the following case:
Fe(NO3 ) (aq) + KOH(aq)→
2
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Homework 4 (Ch 4)
Express your answer as a balanced net ionic equation. Identify all of the phases in your answer.
ANSWER:
Part F
Identify the spectator ion or ions in this reaction.
Express your answer as an ion. If there is more than one answer, separate them by a comma.
ANSWER:
Problem 4.47
Part A
Which region of the periodic table shown here contains elements that are easiest to oxidize?
ANSWER:
A
B
C
D
Part B
Which region contains the least readily oxidized elements?
ANSWER:
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Homework 4 (Ch 4)
A
B
C
D
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