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WorksheetsU10 Redox Test
Total questions: 36
Worksheet time: 26mins
In which compound does chlorine have the highest oxidation number?
NaClO4
NaClO3
NaClO2
NaClO
What is the oxidation number of hydrogen in CaH2?
-2
+1
+2
-1
Oxygen will have a positive oxidation number when combined with
chlorine
bromine
fluorine
iodine
Oxygen has an oxidation number of –1
OH–
H2O2
H2O
H3O+
In an oxidation-reduction reaction, reduction is
defined as the
gain of protons
loss of electrons
loss of protons
gain of electrons
Given the balanced ionic equation:
Which equation represents the oxidation half-
reaction?
Zn(s) + 2e– → Zn2+(aq)
Cu2+(aq) + 2e– → Cu(s)
Zn(s) → Zn2+(aq) + 2e–
Cu2+(aq) → Cu(s) + 2e-
Which change in oxidation number indicates
oxidation?
–1 to +2
+2 to –3
+3 to +2
–1 to –2
Which metal can replace Cr in Cr2O3?
aluminum
lead
nickel
copper
Which particles are gained and lost during a
redox reaction?
electrons
neutrons
protons
positrons
What occurs during the reaction above?
The manganese is reduced and its oxidation
number changes from +2 to +4.
The manganese is oxidized and its oxidation
number changes from +2 to +4.
The manganese is oxidized and its oxidation
number changes from +4 to +2.
The manganese is reduced and its oxidation
number changes from +4 to +2.
Given the redox reaction: Which species serves as the reducing agent?
Sn
Sn2+
Cr3+
Cr
Given the equations A, B, C, and D:
Which two equations represent redox reactions?
A and B
B and C
C and A
D and B
Which element in Period 3 of the Periodic Table
is the strongest reducing agent?
S
Cl
Na
Al
According to Reference Table J, which species
is most easily reduced?
F2(g)
Li(s)
Li+
F–
Base your answer to the following question on
the diagram of a chemical cell and the equation
below. The reaction occurs at 1 atmosphere and
298 K.
Which change occurs when the switch is closed?
Pb is reduced, and electrons flow to the Cu
electrode.
Cu is reduced, and electrons flow to the Pb
electrode.
Cu is oxidized, and electrons flow to the Pb
electrode.
Pb is oxidized, and electrons flow to the Cu
electrode.
According to Reference Table J, which redox
reaction occurs spontaneously?
Cu(s) + 2 H+ → Cu2+ + H2(g)
2 Ag(s) + 2 H+ → 2 Ag + H2(g)
Mg(s) + 2 H+ → Mg2+ + H2(g)
2 Ag(s) + 2 H+ → 2 Ag2+ + H2(g)
Due to it having a low activity, which element
can be found in nature in the free (uncombined)
state?
Ba
Au
Ca
Al
Which metal will undergo the greatest degree
of corrosion if left unprotected from its
surroundings?
nickel
zinc
chromium
iron
Given the balanced equation representing a
redox reaction:
2Al + 3Cu2+ → 2Al3+ + 3Cu
Which statement is true about this reaction?
Each Al3+ gains 3e– and each Cu loses 2e–.
Each Al loses 3e– and each Cu2+ gains 2e–.
Each Al3+ gains 2e– and each Cu loses 3e–.
Each Al loses 2e– and each Cu2+ gains 3e–.
Which equation shows conservation of both
mass and charge?
Cu + 2 Ag+ → Cu2+ + Ag
Cl2 + Br– → Cl– + Br2
Zn + Cr3+ → Zn2+ + Cr
Ni + Pb2+ → Ni2+ + Pb
Given the balanced equation:
3 Fe3+(aq) + Al(s) → 3 Fe2+(aq) + Al 3+(aq)
What is the total number of moles of electrons lost
by 2 moles of Al(s)?
1 mole
6 moles
3 moles
9 moles
Given the unbalanced equation:
__IO3– + 4 H2O + __SO2 → __I2 + __SO4 2– + 8 H+
What is the coefficient of SO2 when the equation
is correctly balanced?
1
2
5
8
Which type of reaction is occurring when a
metal undergoes corrosion?
neutralization
saponification
polymerization
oxidation-reduction
The extent to which the metals zinc and
aluminum corrode is limited because they
form self-protective coatings by neutralization
form self-protective coatings by oxidation
are amphoteric
are semimetals
In a voltaic cell, chemical energy is converted to
nuclear energy, spontaneously
electrical energy, spontaneously
electrical energy, non-spontaneously
nuclear energy, non-spontaneously
The diagram below shows the electrolysis of
fused KCl.
What occurs when the switch is closed?
Positive ions migrate toward the cathode,
where they lose electrons.
Positive ions migrate toward the cathode,
where they gain electrons.
Positive ions migrate toward the anode, where
they lose electrons.
Positive ions migrate toward the anode, where
they gain electrons.
The overall reaction in a electrochemical cell is
Zn(s) + Cu2+(aq) → Zn2+(aq) + Cu(s).
As the reaction in this cell takes place, the
mass of the Cu(s) electrode decreases
Cu2+ (aq)concentration remains the same
mass of the Zn(s) electrode decreases
Zn2+(aq) concentration remains the same
A chemical cell differs from an electrolytic cell
because in a chemical cell there is
an electric current that causes a redox reaction
a positive and negative electrode
a redox reaction that produces an electric
current
an anode and a cathode
Given the lead-acid battery reaction:
As the lead-acid battery discharges, sulfuric acid is a
reactant, with decreasing concentration
product, with decreasing concentration
reactant, with increasing concentration
product, with increasing concentration
When an electrochemical cell is operating, it is
undergoing oxidation, only
undergoing reduction, only
approaching equilibrium
using external energy
Which half-reaction can occur at the anode in a
voltaic cell?
Sn + 2e- →Sn2+
Ni2+ + 2e- → Ni
Fe3+ → Fe2+ + e-
Zn → Zn2+ + 2e-
Where does oxidation occur in an
electrochemical cell?
at the anode in both an electrolytic cell and a
voltaic cell
at the cathode in both an electrolytic cell and a
voltaic cell
at the cathode in an electrolytic cell and at the
anode in a voltaic cell
at the anode in an electrolytic cell and at the
cathode in a voltaic cell
What is the purpose of the salt bridge in a
voltaic cell?
It is a path for the flow of electrons.
It is a path for the flow of positive and
negative ions.
It blocks the flow of electrons.
It blocks the flow of positive and negative ions.
Base your answers to questions 34 and 35 on the
information below.
Two chemistry students each combine a
different metal with hydrochloric acid. Student
A uses zinc, and hydrogen gas is readily
produced. Student B uses copper, and no
hydrogen gas is produced.
State one chemical reason for the different
results of students A and B.
Using Reference Table J, identify another metal that will react with hydrochloric acid to yield hydrogen gas.
Base your answers to the following questions on the information below.
A student constructed an electrochemical cell shown below. One cell contains a strip of magnesium and the other a strip of zinc. The concentration of both solutions is 1.0 mol/L.
a Write the half-reaction that will occur in the cell with the magnesium strip.
b Draw above the voltmeter an arrow indicating the direction that the electrons will flow when the switch is closed.
c As the reaction proceeds the voltage will eventually drop to zero. Explain.
d What is the purpose of the salt bridge joining each half-cell?
