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WorksheetsTopic 9 Redox
Total questions: 86
Worksheet time: 6hrs 16mins
The following occurs when metal X is added to Y sulfate solution and Z sulfate solution. (X, Y and Z represent metal elements but not their symbols.)
X (s) + YSO4 (aq) → XSO4 (aq) + Y (s)
X (s) + ZSO4 (aq): no reaction
What is the order of increasing reactivity?
X < Y < Z
Y < X < Z
Z < Y < X
Z < X < Y
Which is the species oxidized and the oxidizing agent in the reaction?
MnO2 (s) + 4HCl (aq) → MnCl2 (aq) + Cl2 (g) + 2H2O (l)
A
B
C
D
Which species contains nitrogen with the highest oxidation state?
NO3−
NO2−
NO2
N2O
Which compound contains sulfur with an oxidation state of +6?
SO2
H2S
H2SO3
H2SO4
Which is correct for the reaction?
P4 (s) + 3H2O (l) + 3OH− (aq) → PH3 (g) + 3H2PO2− (aq)
A
B
C
D
Which represents a reduction?
SO3 to SO42−
Mn2O3 to MnO2
H2O2 to OH−
CrO42− to Cr2O72−
Which equation shows oxygen undergoing reduction?
2F2 + O2 → 2F2O
Na2O + H2O → 2NaOH
H2O2 + 2HI → 2H2O + I2
2CrO42− + 2H+ ⇌ Cr2O72− + H2O
Which coefficients correctly balance this redox equation?
aFe2+(aq) + MnO4−(aq) + bH+(aq) →
cFe3+(aq) + Mn2+(aq) + dH2O(l)
A
B
C
D
Which element has the same oxidation number in both species?
C in C2H4 and CO2
H in H2O and NaH
S in SO42−and SO3
O in H2O2 and H2O
Which can describe oxidation?
Loss of hydrogen
Decrease in oxidation number
Gain of electrons
Loss of oxygen
What are the oxidation states of chromium in (NH4)2Cr2O7 (s) and Cr2O3 (s)?
A
B
C
D
Which of the following is a redox reaction?
3Mg (s) + 2AlCl3 (aq) → 2Al (s) + 3MgCl2 (aq)
SiO2 (s) + 2NaOH (aq) → Na2SiO3 (aq) + H2O (l)
KCl (aq) + AgNO3 (aq) → AgCl (s) + KNO3 (aq)
2NaHCO3 (aq) → Na2CO3 (aq) + CO2 (g) + H2O (l)
What is the order of decreasing reactivity of the metals (most reactive first)?
Zn(s) + Sn2+(aq) → Zn2+(aq) + Sn(s)
Cu(s) + Zn2+(aq) → No Reaction
Sn(s) + Cu2+(aq) → Sn2+(aq) + Cu(s)
Ag(s) + Cu2+(aq) → No Reaction
Zn > Cu > Sn > Ag
Sn > Zn > Ag > Cu
Ag > Cu > Zn > Sn
Zn > Sn > Cu > Ag
What is the oxidation half-equation in the redox reaction?
2S2O32–(aq) + I2(aq) → S4O62–(aq) + 2I–(aq)
I2(aq) + 2e– → 2I–(aq)
2I–(aq) → I2(aq) + 2e–
2S2O32–(aq) → S4O62–(aq) + 2e–
S4O62–(aq) + 2e– → 2S2O32–(aq)
Which of the following does not react with dilute HCl(aq)?
Na2CO3
Cu
Zn
CuO
Which element is reduced in the following decomposition?
(NH4)2Cr2O7(s) → N2(g) + Cr2O3(s) + 4H2O(g)
N
H
Cr
O
Which of the following is not a redox reaction?
CH4(g) + Cl2(g) → CH3Cl(g) + HCl(g)
C(s) + O2(g) → CO2(g)
2CO(g) → CO2(g) + C(s)
CH3COOH(aq) + NaOH(aq) → CH3COONa(aq) + H2O(l)
Consider the above half-equations:
Which statement is correct for the reaction between KMnO4 (aq) and KI (aq) in acidic conditions?
MnO4– reduces I– to I2.
I– reduces MnO4– to Mn2+.
The colour changes from brown to purple.
MnO4– is oxidized to Mn2+.
Which change represents oxidation?
HClO4 to HClO3
N2 to NH3
N2O to NO
SO42− to SO32−
A reaction takes place when a rechargeable battery is used:
Pb(s) + PbO2(s) + 4H+(aq) + 2SO42−(aq) →
2PbSO4(s) + 2H2O(l)
Which statements are correct?
I. H+ is reduced
II. The oxidation state of Pb metal changes from 0 to +2
III. PbO2 is the oxidising agent
I and II only
I and III only
II and III only
I, II and III
Which compounds can be reduced?
I. C2H4
II. CH3COOH
III. CH3CHO
I and II only
I and III only
II and III only
I, II and III
Which experimental methods could be used to observe the progress of the following reaction?
Cr2O72-(aq) + 6I-(aq) + 14H+(aq) →
2Cr3+(aq) + 3I2(aq) + 7H2O(l)
I. Change in colour
II. Change in mass
III. Change in electrical conductivity
I and II only
I and III only
II and III only
I, II and III
Applying IUPAC rules, what is the name of MnO2?
Magnesium(II) oxide
Manganese(II) oxide
Magnesium(IV) oxide
Manganese(IV) oxide
Which is a correct statement for the reaction below?
2MnO4-(aq) + 6H+(aq) + 5NO2-(aq) →
2Mn2+(aq) + 5NO3-(aq) + 3H2O(l)
MnO4- is the reducing agent and the oxidation number of Mn increases.
MnO4- is the oxidizing agent and the oxidation number of Mn decreases.
NO2- is the reducing agent and the oxidation number of N decreases.
NO2- is the oxidizing agent and the oxidation number of N increases.
Which represents a redox reaction?
NaH(s)+H2O(l)→NaOH(aq)+H2(g)
CaCO3(s)→CaO(s)+CO2(g)
CuCl2(aq)+K2S(aq)→CuS(s)+2KCl(aq)
HCl(aq)+NH3(aq)→NH+4CL−(aq)
Which species can oxidize ethanol to ethanoic acid?
I−
Fe
O2−
Acidified K2Cr2O
What are the oxidation states of each element in K2CrO4?
A
B
C
D
What is the coefficient for I– when the following equation is balanced using the smallest possible whole numbers?
IO3−(aq)+ ___ I−(aq)+ ___ H+(aq)→ ___ I2(aq)+ ___ H2O(l)
1
2
3
5
Which represents a redox reaction?
NaH(s)+H2O(l)→NaOH(aq)+H2(g)
CaCO3(s)→CaO(s)+CO2(g)
CuCl2(aq)+K2S(aq)→CuS(s)+2KCl(aq)
HCl(aq)+NH3(aq)→NH+4Cl−(aq)
Which is a redox reaction?
[Cu(H2O4]2+(aq) + 4Cl−(aq) → [CuCl4]2−(aq) + 4H2O(l)
Ag+(aq) + Cl−(aq) → AgCl(s)
Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2(g)
2K2CrO4(aq) + 2HCl(aq) → K2Cr2O7(aq) + H2O(l) + 2KCl(aq)
Which species of vanadium has a different oxidation number from the rest?
VO2+
VO−3
V2O5
VO2+
Which statement is correct for the following reaction?
2ClO3−(aq) + SO2(aq) + H+(aq) →
2ClO2(g) + HSO4− (aq)
ClO3− is the oxidizing agent and it undergoes reduction.
ClO3− is the reducing agent and it undergoes oxidation.
SO2 is the oxidizing agent and it undergoes oxidation.
SO2 is the reducing agent and it undergoes reduction.
At which side of the equation are electrons, H+ ions and H2O needed to complete the half-equation?
MnO4−(aq) → Mn2+(aq)
A
B
C
D
What are the correct names for KMnO4 and K2Cr2O7, using oxidation numbers?
Potassium permanganate and potassium dichromate
Potassium manganate(IV) and potassium chromate(VII)
Potassium permanganate(IV) and potassium dichromate(VII)
Potassium manganate(VII) and potassium dichromate(VI)
What are the correct oxidation numbers of chromium in Cr2O72− and manganese in KMnO4?
A
B
C
D
Which species are the oxidizing and reducing agents in the following reaction?
SO32−(aq)+PbO2(s)+H2O(l)→SO42−(aq)+Pb(OH)2(s)
A
B
C
D
What is the name of Co3(PO4)2?
Cobalt(II) phosphite
Cobalt(II) phosphate
Cobalt(III) phosphite
Cobalt(III) phosphate
Consider the following reaction.
Sn(s)+4HNO3(aq)→SnO2(s)+4NO2(g)+2H2O(g)
Which statement is correct?
HNO3 is the oxidizing agent because it undergoes oxidation.
HNO3 is the reducing agent because the oxidation number of nitrogen changes from +5 to +4.
Sn is the oxidizing agent because it undergoes reduction.
Sn is the reducing agent because the oxidation number of tin changes from 0 to +4.
Which statement is correct about a reducing agent?
It is reduced by gaining electrons.
It is oxidized by gaining electrons.
It is oxidized by losing electrons.
It is reduced by losing electrons.
What is the correct increasing order of reactivity of the metals X, Y and Z based on the following information?
XCl2 + Y → YCl2X
ZCl2 + X → XCl2Z
YCl2 + Z → no reaction
Z < X < Y
Y < X < Z
Z < Y < X
X < Z < Y
Which statement describes a reducing agent?
It is reduced and gains electrons.
It is reduced and loses electrons.
It is oxidized and gains electrons.
It is oxidized and loses electrons.
Which is the oxidizing agent in the following reaction?
5SO2(g) + 2IO3−(aq) + 4H2O(l) →
5SO42−(aq) + I2(aq) + 8H+(aq)
SO2
IO3−
H2O
SO42−
Consider the following reaction.
2Cr(OH)3(s) + 6ClO−(aq) →
2CrO42−(aq) + 3Cl2 (g) + 2OH−(aq) + 2H2O(l)
Which statement is correct?
Cr(OH)3 is the oxidizing agent and the oxidation number of chromium changes from +3 to +6.
Cr(OH)3 is the reducing agent and undergoes reduction.
ClO− is the oxidizing agent and the oxidation number of chlorine changes from +1 to 0.
ClO− is the reducing agent and the oxidation number of chlorine changes from –1 to 0.
What is the name of Cu2S?
Copper(I) sulfide
Copper(I) sulfate
Copper(II) sulfide
Copper(II) sulfate
Consider the following reaction:
3(aq) + Cr2O72−(aq) + 2H+(aq) →
2Cr3+(aq) + 3SnO2(s) + H2O(l)
Which statement is correct?
Sn2+ is the oxidizing agent because it undergoes oxidation.
Sn2+ is the reducing agent because it undergoes oxidation.
Cr2O72− is the oxidizing agent because it undergoes oxidation.
Cr2O72− is the reducing agent because it undergoes oxidation.
What is the correct decreasing order of reactivity of the metals X, Y and Z based on the following equations?
XCl + Y → YCl + X
YCl + Z → YCl + Z
ZCl + X → XCl + Z
X > Y > Z
Y > Z > X
Z > Y > X
Y > X > Z
Which of the following redox reactions take place?
I. Cl2(aq) + 2NaI(aq) → I2(aq) + 2NaCl(aq)
II. Br2(aq) + 2NaI(aq) → I2(aq) + 2NaBr(aq)
III. I2(aq) + 2NaBr(aq) → Br2(aq) + 2NaI(aq)
I and II only
I and III only
II and III only
I, II and III
Which species could be reduced to form NO2?
N2O
NO−3
HNO2
NO
What happens to the manganese in the following reaction?
2MnO4−(aq) + 5H2O2(aq) + 6H+(aq) →
2Mn2+(aq) + 8H2O(l) + 5O2(g)
It is oxidized and its oxidation number increases.
It is oxidized and its oxidation number decreases.
It is reduced and its oxidation number increases.
It is reduced and its oxidation number decreases.
What happens to iodine when iodate ions, IO3−, are converted to iodine molecules, I2?
It undergoes reduction and its oxidation number changes from −1 to 0
It undergoes oxidation and its oxidation number changes from −1 to 0
It undergoes reduction and its oxidation number changes from +5 to 0
It undergoes oxidation and its oxidation number changes from +5 to 0
Consider the following reactions of three unknown metals X, Y and Z.
2XNO3(aq) + Y(s) → 2X(s) + Y(NO3)2((aq)
Y(NO3)2(aq) + Z(s) → No reaction
2XNO3(aq) + Z(s) → 2X(s) +Z (NO3)2((aq)
What is the order of increasing reactivity of the metals (least reactive first)?
X < Y < Z
X < Z < Y
Z < Y < X
Y < Z < X
What is the correct order of reaction types in the following sequence?
A
B
C
D
Consider the following reaction.
MnO4−(aq) + 8H+(aq) + 5Fe2+(aq) →
Mn2+(aq) + 5Fe3+(aq) + 4H2O(l)
Which statement is correct?
MnO4− is the oxidizing agent and it loses electrons.
MnO4− is the reducing agent and it loses electrons.
MnO4− is the oxidizing agent and it gains electrons.
MnO4− is the reducing agent and it gains electrons.
In which species does sulfur have an oxidation number of 0?
SO3
S8
Na2SO4
H2S
What is the reducing agent in the reaction below?
2MnO4−(aq) + Br−(aq) + H2O(l) →
2MnO2(s) + BrO3−(aq) + 2OH−(aq)
Br−
BrO3−
MnO4−
MnO2
The following equations indicate reactions that occur spontaneously.
Fe(s) + NiCl2(aq) → FeCl2(aq) + Ni(s)
Zn(s) + FeCl2(aq) → ZnCl2(aq) + Fe(s
Ni(s) + PbCl2(aq) → NiCl2(aq) + Pb(s)
Which is the increasing order of the reactivity of the metals?
Fe < Ni < Zn < Pb
Pb < Ni < Fe < Zn
Ni < Zn < Pb < Fe
Zn < Fe < Ni < Pb
Which are redox reactions?
I. 2FeCl2 + Cl2 → 2FeCl3
II. Mg + 2HNO3 → Mg(NO3)2 + H2
III. H2O + SO3 → H2SO4
I and II only
I and III only
II and III only
I, II and III
Metal M has only one oxidation number and forms a compound with the formula MCO3. Which formula is correct?
MNO3
MNH4
MSO4
MPO4
Which species is oxidized in the following reaction?
2Ag+(aq) + Cu(s) → 2Ag(s) + Cu2+(aq)
Ag+
Cu
Ag
Cu2+
Which list represents the halogens in increasing order of oxidizing strength (weakest oxidizing agent first)?
Cl2 - I2 - Br2
I2 - Br2 - Cl2
I2 - Cl2 - Br2
Cl2 - Br2 - I2
What is formed at the electrodes during the electrolysis of molten sodium bromide?
A
B
C
D
Where does oxidation occur in a voltaic cell?
positive electrode and anode
negative electrode and anode
positive electrode and cathode
negative electrode and cathode
Which product will be obtained at the anode (positive electrode) when molten NaCl is electrolysed?
Na (l)
Cl (g)
Cl2 (g)
Na (s)
Consider this electrochemical cell. What happens to the ions in the salt bridge when a current flows?
Na+ ions flow to the zinc half-cell and SO42− ions flow to the copper half-cell.
Na+ ions flow to the copper half-cell and SO42− ions flow to the zinc half-cell.
Na+ and SO42− ions flow to the copper half-cell.
Na+ and SO42− ions flow to the zinc half-cell.
This reaction occurs in a voltaic (galvanic) cell.
Mg (s) + 2Ag+ (aq) → Mg2+ (aq) + 2Ag (s)
Which reaction takes place at each electrode?
A
B
C
D
What are the products of electrolysis of concentrated aqueous sodium bromide?
A
B
C
D
Which product will be obtained at the anode (positive electrode) when molten NaCl is electrolysed?
Na (l)
Cl (g)
Cl2 (g)
Na (s)
Where does oxidation occur in a voltaic cell?
positive electrode and anode
negative electrode and anode
positive electrode and cathode
negative electrode and cathode
The following reaction occurs in a voltaic (galvanic) cell.
Mg (s) + 2Ag+ (aq) → Mg2+ (aq) + 2Ag (s)
Which reaction takes place at each electrode?
A
B
C
D
Which describes the flow of electrons in a voltaic cell?
From the cathode (positive electrode) to the anode (negative electrode) through the external circuit
From the anode (negative electrode) to the cathode (positive electrode) through the external circuit
From the oxidizing agent to the reducing agent through the salt bridge
From the reducing agent to the oxidizing agent through the salt bridge
What are the products of electrolysis when molten calcium bromide is electrolysed using graphite electrodes?
A
B
C
D
What are the products of the electrolysis of molten zinc bromide?
A
B
C
D
What is the reaction type and major product at the anode (positive electrode) when molten sodium chloride is electrolysed using platinum electrodes?
A
B
C
D
Which statements are correct for a voltaic cell?
I. A spontaneous redox chemical reaction produces electrical energy.
II. Oxidation occurs at the cathode (negative electrode).
III. Electrons flow from anode (negative electrode) to cathode (positive electrode).
I and II only
I and III only
II and III only
I, II and III
What occurs at the anode (positive electrode) during the electrolysis of molten strontium bromide?
Formation of bromine and oxidation
Formation of bromine and reduction
Formation of strontium and oxidation
Formation of strontium and reduction
A voltaic cell is constructed from zinc and copper half-cells. Zinc is more reactive than copper. Which statement is correct when this cell produces electricity?
Electrons flow from the copper half-cell to the zinc half-cell.
The concentration of Cu2+ (aq) increases.
Electrons flow through the salt bridge.
Negative ions flow through the salt bridge from the copper half-cell to the zinc half-cell.
Which statement is correct for a voltaic but not for an electrolytic cell?
An electrolyte is required.
The anode is where oxidation occurs.
Electrons flow from the negative electrode to the positive electrode.
Electrons flow from the negative electrode to the positive electrode.
Two half-cells are connected via a salt bridge to make a voltaic cell. Which statement about this cell is correct?
Oxidation occurs at the positive electrode (cathode).
It is also known as an electrolytic cell.
Ions flow through the salt bridge.
It requires a power supply to operate.
A voltaic cell is made by connecting a copper half-cell,
Cu(s) ∣ Cu2+(aq), to an iron half-cell Fe(s) ∣ Fe2+(aq).
Which combination correctly identifies the positive electrode and the species being oxidized?
Copper is the positive electrode; Iron is oxidized
Copper is the positive electrode; Copper (II) ions are oxidized
Iron is the positive electrode; Copper is oxidized
Iron is the positive electrode; Copper (II) ions are oxidized
Which statement about an electrolytic cell is correct?
Chemical energy is converted to electrical energy.
Electrons move through the electrolyte.
The cathode is the negative electrode.
The negative ions move towards the negative electrode.
At which electrodes does oxidation occur in a voltaic cell and in an electrolytic cell?
A
B
C
D
Zinc is more reactive than copper. In this voltaic cell, which species is reduced and in which direction do negative ions flow in the salt bridge?
Cu2+ is reduced; negative ions flow from copper half-cell to zinc half-cell
Cu2+ is reduced; negative ions flow from zinc half-cell to copper half-cell
Zn2+ is reduced; negative ions flow from copper half-cell to zinc half-cell
Zn2+ is reduced; negative ions flow from zinc half-cell to copper half-cell
Which process occurs when a molten salt is electrolysed?
The metal ion is oxidized and deposited on the negative electrode (cathode).
The metal ion is reduced and deposited on the negative electrode (cathode).
The metal ion is oxidized and deposited on the positive electrode (anode).
The metal ion is reduced and deposited on the positive electrode (anode).
Which species are produced at each electrode during the electrolysis of molten lead(II) bromide, PbBr2(l)?
A
B
C
D
Which statements are correct for the electrolysis of molten lead(II) bromide, PbBr2(l)?
I. Pb2+ is reduced at the negative electrode (cathode).
II. Br− is oxidized at the positive electrode (anode).
III. Bubbles of a brown gas are observed at the negative electrode (cathode).
I and II only
I and III only
II and III only
I, II and III
Which are correct statements about a voltaic cell?
I. A spontaneous redox reaction occurs which converts chemical energy to electrical energy.
II. Oxidation occurs at the negative electrode (anode).
III. Electricity is conducted by the movement of electrons through the salt bridge.
I and II only
I and III only
II and III only
I, II and III
