Which row correctly describes oxidation and reduction in terms of electron transfer and changes in oxidation state?
| Electron transfer | Change in oxidation state | ||
| oxidation | reduction | oxidation | reduction |
A B C D | gain loss loss gain | loss gain loss gain | increase increase decrease decrease | decrease decrease increase increase |
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Which are the correct common oxidation states of fluorine, oxygen and hydrogen in compounds?
| Fluorine | Oxygen | Hydrogen |
A | - 1 | - 2 | + 1 |
B | - 7 | - 1 | - 1 |
C | + 1 | + 2 | + 1 |
D | + 7 | - 1 | - 1 |
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The heptahydrate mineral of magnesium sulfate is used in Epsom Salts for preparing therapeutic baths. Magnesium sulfate is also used in some medical applications.
What is the overall oxidation state of MgSO4?
-2
+2
+7
0
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Which compound shows nitrogen in the highest oxidation state?
NaNO2
N2O4
N2O
NO
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Sulfur dioxide and oxygen difluoride react together. The oxidation state of fluorine in OF2 is -1.
SO2 + OF2 format('truetype')%3Bfont-weight%3Anormal%3Bfont-style%3Anormal%3B%7D%3C%2Fstyle%3E%3C%2Fdefs%3E%3Ctext%20font-family%3D%22math12bba9f4124283edd644799e0ce%22%20font-size%3D%2216%22%20text-anchor%3D%22middle%22%20x%3D%2210.5%22%20y%3D%2216%22%3E%26%23x2192%3B%3C%2Ftext%3E%3C%2Fsvg%3E){kind=small}
SO3 + F2
Using oxidation states, which description about the elements is correct?
| Sulfur | Fluorine |
A | Oxidised | Reduced |
B | Reduced | Oxidised |
C | Oxidised | Oxidised |
D | Reduced | Reduced |
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Which equation does not represent a redox reaction?
FeO + 2HCl FeCl2 + H2O
Mg + CuSO4 MgSO4 + Cu
Ca + 2HCl CaCl2 + H2
C2H4 + 3O2 2CO2 + 2H2O
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Which of these is a redox reaction?
KBr + H2SO4 ⟶ KHSO4 + HBr
Ca + S ⟶ CaS
Li2O + H2SO4 ⟶ Li2SO4 + H2O
MgO + SiO2 ⟶ MgSiO3
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Which reaction shows hydrogen acting as an oxidising agent?
H2 + Br2 → 2HBr
H2 + C3H6O → C3H7OH
2H2 + O2 → 2H2O
H2 + 2Li → 2LiH
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Which of the following species contains the metal with the highest oxidation state?
MnO4-
TiO2
Cr2O72-
V2O5
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Which of the following statements is correct for a reducing agent?
A reducing agent undergoes reduction
A reducing agent is an electron acceptor
A reducing agent is an electron donor
A reducing agent decreases in oxidation state
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Which statement about the redox chemistry of Group 7 is correct?
Bromine can oxidise chloride ions
In reactions with water, chlorine is oxidised and reduced
Iodide ions are the weakest reducing agent of the first four Group VII ions
Fluorine is a weaker oxidising agent than chlorine
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Which reaction shows the species in bold acting as an oxidising agent?
2MnO4- + 5SO32- + 6H+ → 2Mn2+ + 3H2O + 5SO42-
Fe2O3 + 3CO → 2Fe + 3CO2
Cl2 + 2Br- → 2Cl- + Br2
Mg + Fe2+ → Mg2+ + Fe
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In which compound are there two different elements with the same oxidation state?
NH4Cl
Na2SO4
Mg(OH)2
HClO
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Sulfuric acid and sodium bromide can react according to the following equation.
2NaBr (s) + 3H2SO4 (aq) 2NaHSO4 (s) + SO2 (g) + Br2 (g) + 2H2O (l)
Which species has been oxidised in this reaction?
H+
Na+
Br−
SO42−
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The following reaction can be used to determine the mass of titanium dioxide in an ore.
3TiO2 + 4BrF3 3TiF4 + 2Br2 + 3O2
Which element decreases in oxidation state in this reaction?
fluorine
bromine
titanium
oxygen
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In which reaction does hydrogen behave as an oxidising agent?
H2 + CuO → Cu + H2O
2Na + H2 → 2NaH
H2 + Cl2 → 2HCl
C2H4 + H2 → C2H6
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Chlorine gas forms different products when it reacts with hot and cold aqueous sodium hydroxide.
What are the correct oxidation numbers of chlorine in the products of these reactions?
| Hot aqueous sodium hydroxide | Cold aqueous sodium hydroxide |
A B C D | +1, +6 +1, +6 -1, +5 -1, +5 | -1, +1 -1, +2 -1, +1 -1, +2 |
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Concentrated sulfuric acid can react with potassium halides according to the following equations.
Reaction 1: 8KI + 5H2SO4 → 4K2SO4 + H2S + 4I 2 + 4H2O
Reaction 2: 2KBr + 2H2SO4 → K2SO4 + SO2 + Br2 + 2H2O
Reaction 3: KCl + H2SO4 → KHSO4 + HCl
For each reaction, what is the largest change in the oxidation number of sulfur?
| Reaction 1 | Reaction 2 | Reaction 3 |
A | 8 | 4 | 1 |
B | 8 | 2 | 0 |
C | 4 | 2 | 0 |
D | 4 | 1 | 1 |
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Vanadium (V) oxide, V2O5, acts as a catalyst in the Contact Process, making sulfuric acid.
During one step of the Contact Process, the vanadium (V) oxide changes from the V5+ to the V4+ oxidation state which causes sulfur dioxide to be oxidised to sulfur trioxide.
Which is the correct formula of the V4+ intermediate species that is formed during the Contact Process?
VO43-
V2O4
VO3-
VO2+
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Titanium dioxide can be obtained from the ore ilmenite, Fe(II)TiO3.
FeTiO3 → TiO2
What is the change in the oxidation number of titanium in the reaction?
+3 to +4
+4 to +5
+6 to +4
No change in oxidation number occurs
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A solution containing both bromine and chlorine will produce bromate ions, BrO3–.
The reactions leading to the production of BrO3– ions are:
1: Br2 + H2O → HBr + HBrO
2: 3HBrO + Cl2 → 2Cl – + BrO3– + Br2 + 3H+
Which statements about these reactions are correct?
| Chlorine is reduced in reaction 2 | Bromine is reduced in both reaction 1 and reaction 2 | Bromine is oxidised in both reaction 1 and reaction 2 |
A | ✓ | X | X |
B | ✓ | ✓ | X |
C | X | ✓ | ✓ |
D | ✓ | ✓ | ✓ |
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If a dilute acid is added to an aqueous solution containing nitrite ions, NO2–, two different nitrogen compounds are released as gases.
2H+ (aq) + 2NO2– (aq) → H2O (l) + NO (g) + NO2 (g)
Which of the three statements below correctly describe the process?
| The H+ (aq) ion is oxidised by NO2–(aq). | Some nitrogen atoms are oxidised, and some nitrogen atoms are reduced. | The H+ (aq) ion acts as a catalyst. |
A | ✔ | ✔ | X |
B | X | ✔ | X |
C | X | ✔ | ✔ |
D | ✔ | ✔ | ✔ |
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What are the correct oxidation states for the elements in Fe3O4?
| Fe | O |
A | +3 and +4 | -1 |
B | +2.67 | -2 |
C | +2 and +3 | -2 |
D | +4 | -3 |
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In terms of electron transfer, what does an oxidising agent do in a redox reaction?
Accept electrons
Donate electrons
Accept a pair of electrons
Donate a pair of electrons
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Which species is the best oxidising agent?
F-
Cl -
F2
Cl2
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Potassium dichromate reacts with ethanedioic acid and sulfuric acid to form chromium (III) sulfate, potassium sulfate and two other products.
What is the reducing agent for this reaction?
H+
K+
C2O42-
Cr2O72-
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Iron (II) sulfate reacts with potassium manganate (VII) in acidic conditions to produce iron (III) sulfate, manganese sulfate, potassium sulfate and water.
The unbalanced equation for this reaction is shown below.
_FeSO4 + _KMnO4 + _H2SO4 → _Fe2(SO4)3 + _MnSO4 + _H2O + K2SO4
Which whole number stoichiometric coefficients are correct to balance the equation?
| FeSO4 | KMnO4 | H2SO4 | Fe2(SO4)3 | MnSO4 | H2O |
A | 10 | 2 | 8 | 5 | 2 | 8 |
B | 10 | 2 | 4 | 5 | 2 | 8 |
C | 5 | 2 | 8 | 5 | 1 | 4 |
D | 5 | 1 | 4 | 5 | 1 | 4 |
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Chromate (VII) and dichromate (VII) ions are both oxidising agents with chromium in the +6 oxidation state.
Which equation shows the correct ionic half equation for the chromate ion to form Cr3+?
CrO4- + 8H+ + 2e- → Cr3+ + 4H2O
Cr2O72- + 14H+ + 6e- → Cr3+ + 7H2O
CrO42- + 8H+ + 5e- → Cr3+ + 4H2O
CrO42- + 8H+ + 3e- → Cr3+ + 4H2O
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Which one of the following is the electron arrangement of the strongest oxidising agent?
1s2 2s2 2p4
1s2 2s2 2p6 3s2 3p3
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p5
1s2 2s2 2p6 3s2 3p6
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Potassium manganate (VII) reacts with hydrogen peroxide and sulfuric acid to form potassium sulfate, manganese sulfate, oxygen and water.
Which species is acting as the reducing agent in the reaction?
MnO4-
H2O2
H+
SO42-
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