Magnesium is oxidized, copper is reduced,

thomas (tt9669) – Post-lab 6 Copper Cycle – lyon – (51730)
This print-out should have 30 questions.
Multiple-choice questions may continue on
the next column or page – find all choices
before answering.
001 10.0 points
If the percent yield of the copper was determined to be 85% at the end of the procedure
but there was obvious aluminum contamination in the dried product, it is not necessary to
note it in the lab report that the percent yield
is high. It does not matter what is in the final product, only the final mass is important,
even if there is contamination.

1

2. Magnesium is oxidized, copper is reduced,
and silver is neither oxidized nor reduced.
3. Magnesium is oxidized; copper and silver
are reduced.
4. Magnesium and silver are oxidized; copper is reduced.
004

10.0 points

The reaction
H2 CN2 (g) + heat → N2 (g) + CH2 (g)
is an example of a

1. False

1. decomposition reaction.

2. True

2. combustion and precipitation reaction.

002 10.0 points
Consider the process in which H2 SO3 is converted to H2 SO4 . The oxidation state of oxygen remains −2, and the oxidation state of H
remains +1. Select the correct statement.
1. S neither gains nor loses electrons in this
reaction.
2. S is reduced and loses electrons.
3. S is oxidized and gains electrons.

3. combustion reaction.
4. displacement reaction.
5. combination reaction.
005 10.0 points
Which of the following is a list of the four
types of reactions that occurred during the
copper cycle procedure?
1. Precipitation, acid-base, synthesis and
decomposition

4. S is oxidized and loses electrons.
5. S is reduced and gains electrons.

2. Oxidation-reduction, acid-base, decomposition and synthesis

003 10.0 points
Consider the metals in the following reactions.

3. Oxidation-reduction, precipitation, acidbase and decomposition

2 Mg + O2 → 2 MgO

4. Oxidation-reduction, precipitation, acidbase and synthesis

CuO + H2 → Cu + H2 O
Ag+ + Cl− → AgCl
Which of the following is true?
1. Magnesium is reduced; copper and silver
are neither oxidized nor reduced.

006 10.0 points
Determine the oxidation state of Sn in SnO−2
3
given the oxidation number of O = −2.
1. +3
2. −2

thomas (tt9669) – Post-lab 6 Copper Cycle – lyon – (51730)

2

4. combustion
3. +8
010 10.0 points
Copper is an oxidizing agent in one of the
redox reactions and is a reducing agent in
the other redox reaction in the copper cycle
procedure.

4. +4
5. +6
007 10.0 points
Out of the four types of reactions that occurred in the copper cycle procedure, which
type of reaction produces aqueous CuSO4 and
liquid H2 O?
1. Acid-base neutralization
2. Oxidation-reduction

1. True
2. False
011 10.0 points
Which of the following substances is the oxidizing agent in the last redox reaction copper
cycle procedure?

3. Synthesis

1. Al

4. Precipitation

2. CuSO4

5. Decomposition

3. HCl

008 10.0 points
Identify the type of reaction represented by
the chemical equation
PbCl2 (aq) + Li2 SO4 (aq) →
2 LiCl(aq) + PbSO4 (s)
1. All of the choices are correct.
2. redox
3. single displacement
4. precipitation
009 10.0 points
Classify the reaction
2 HgO(s) → 2 Hg( ) + O2 (g) .

4. H2 SO4
012 10.0 points
Assign oxidation numbers to each atom in
NH+ .
4
1. N = +1, H = +1
2. N = −2, H = +1
3. N = −3, H = +1
4. N = +3, H = −1
5. N = −1, H = +1
013 10.0 points
Consider the following half reaction in a redox
reaction in the copper cycle.

1. decomposition

2 H+ + NO− + 1 e− → NO2 + H2 O
3

2. water forming

Which of the following statements best describes the chemistry of the half-reaction?

3. synthesis
1. The nitrate ion is gaining electrons and is

thomas (tt9669) – Post-lab 6 Copper Cycle – lyon – (51730)
the reducing agent.

In the reaction

2. The nitrate ion is oxidized and is the
reducing agent.
3. The nitrate ion is losing electrons and is
the oxidizing agent.
4. The nitrate ion is reduced and is the
oxidizing agent.
014
In the reaction

3

Cu2+ + Fe → Cu + Fe2+
1. iron is oxidized.
2. iron is reduced.
3. copper(II) is the reducing agent.
4. copper is oxidized.

10.0 points

Cu(s) + 4 HNO3 (aq) →
Cu(NO3 )2 (aq) + 2 NO2 (g) + 2 H2 O ,
what is the oxidizing agent?

018 10.0 points
Which of the following substances is the reducing agent in the last redox reaction copper
cycle procedure?
1. Al2 (SO4 )3

1. NO2

2. HCl

2. Cu(NO3 )2

3. Al

3. HNO3

4. CuSO4

4. Cu
5. This is not a redox reaction.
015 10.0 points
The oxidation numbers of nitrogen in NH3 ,
NO− and NO are
3
1. +3, +6, and +2, respectively.

1. +5
2. −4

2. −3, +5, and +1, respectively.

3. +1

3. −3, +6, and +2, respectively.

4. −1

4. −3, +5, and +2, respectively.
016 10.0 points
When copper metal is oxidized,
(loses/gains) electrons.

019 10.0 points
Determine the oxidation number of S in
Na2 SO3 if the oxidation number of Na is +1
and O is −2.

5. +4
it

020 10.0 points
Classify the reaction
HNO3 (aq) + NaOH(aq) →
H2 O( ) + NaNO3 (aq) .

1. Loses
2. Gains

1. oxidation reduction
017

10.0 points

2. All of the choices are correct.

thomas (tt9669) – Post-lab 6 Copper Cycle – lyon – (51730)
3. precipitation
4. acid-base
021 10.0 points
Copper is a reducing agent in the first step of
the reaction cycle and copper is an oxidizing
agent in the last step of the reaction cycle.
1. True
2. False
022 10.0 points
In one of the reactions of the copper cycle,
CuO is reacted with H2 SO4 . What type of
reaction is this and what kind of reactant is
CuO?
1. Acid-base and CuO is a basic anhydride
2. Oxidation-reduction and CuO is an oxidizing agent

4

uct. It is the purity of the product not the
mass of the product that determines the percent recovery. Contamination will introduce
mass to the copper product and cause the percent recovery to be too high. Loss of copper
during the reaction cycle will cause the percent recovery of the copper product to be too
low.
Describe whether the error introduced by
each of the following five problems would result in a high, low or no affect on the percent
recovery of the original copper sample.
Insufficient NaOH is added in Step 3.
1. No effect
2. Low
3. High
025 (part 2 of 5) 10.0 points
Some solid is lost during the decanting process
in step 5.
1. High

3. Acid-base and CuO is an acid
2. Low
4. Oxidation-reduction and CuO is a reducing agent
023 10.0 points
Determine the oxidation number of carbon in
CO2− . Recall that the oxidation number of
3
oxygen is always −2.

3. No effect
026 (part 3 of 5) 10.0 points
An excess of sulfuric acid is added in step 8.
1. Low

1. +4

2. No effect

2. +2

3. High

3. −6
4. +6

027 (part 4 of 5) 10.0 points
Some unreacted aluminum remains with the
product at the end of the experiment.

5. −2

1. Low

6. −4

2. High

024 (part 1 of 5) 10.0 points
Percent recovery refers to PURE copper prod-

3. No effect

thomas (tt9669) – Post-lab 6 Copper Cycle – lyon – (51730)
028 (part 5 of 5) 10.0 points
The copper is not completely dried bef
ore
weighing.
1. High
2. No effect
3. Low
029 10.0 points
Which response contains all of the following
I) PCl3 + 3 H2 O → 3 HCl + H3 PO3
II) Fe2 O3 + 3 CO → 2 Fe + 3 CO2
III) CaCO3 + 2 HNO3 →
Ca(NO3 )2 + CO2 + H2 O
that are oxidation-reduction reactions and no
others?
1. II and III only
2. I only
3. I and II only
4. II only
5. III only
030 10.0 points
Out of the four types of reactions that occurred in the copper cycle procedure, which
type of reaction produces solid Cu(OH)2 and
aqueous NaNO3 ?
1. Synthesis
2. Decomposition
3. Acid-base neutralization
4. Precipitation
5. Oxidation-reduction

5