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Questions and Answers
In the reaction, MnO4^- + 5Fe^2+ + 8H^+ → Mn^2+ + 5Fe^3+ + ______
In the reaction, MnO4^- + 5Fe^2+ + 8H^+ → Mn^2+ + 5Fe^3+ + ______
4H2O
Oxidation involves an increase in ______ number.
Oxidation involves an increase in ______ number.
oxidation
In the reaction Cd + H^+ + NO3^- → Cd^2+ + NO + ______, nickel oxide is produced.
In the reaction Cd + H^+ + NO3^- → Cd^2+ + NO + ______, nickel oxide is produced.
H2O
The reducing agent in the reaction is ______.
The reducing agent in the reaction is ______.
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In the redox reaction 8Al + 3Fe3O4 → 4Al2O3 + 9Fe, ______ is reduced.
In the redox reaction 8Al + 3Fe3O4 → 4Al2O3 + 9Fe, ______ is reduced.
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Oxidation occurs when an element loses ______.
Oxidation occurs when an element loses ______.
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Reduction occurs when an element gains ______.
Reduction occurs when an element gains ______.
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In the reaction 2Na + Cl2, each Na loses one ______.
In the reaction 2Na + Cl2, each Na loses one ______.
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Zn acts as a ______ agent by donating electrons to Cu^2+.
Zn acts as a ______ agent by donating electrons to Cu^2+.
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Cu^2+ is an example of an ______ agent.
Cu^2+ is an example of an ______ agent.
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The oxidation number of any un-combined element is ______.
The oxidation number of any un-combined element is ______.
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In the equation for the disinfecting of water, Cl2 is the ______ agent.
In the equation for the disinfecting of water, Cl2 is the ______ agent.
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Oxidation and reduction reactions are also known as ______ reactions.
Oxidation and reduction reactions are also known as ______ reactions.
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An un-combined element is an element that is not bonded to another element, e.g., Zn, Fe, ______.
An un-combined element is an element that is not bonded to another element, e.g., Zn, Fe, ______.
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The oxidation number of an ion of an element is the same as its ______.
The oxidation number of an ion of an element is the same as its ______.
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The sum of the oxidation numbers of all of the elements in a compound must add up to ______.
The sum of the oxidation numbers of all of the elements in a compound must add up to ______.
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Oxygen always has an oxidation number of ______ except in peroxides and in the compound OF2.
Oxygen always has an oxidation number of ______ except in peroxides and in the compound OF2.
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Hydrogen is always assigned an oxidation number of ______ in its compounds except in the metal hybrids.
Hydrogen is always assigned an oxidation number of ______ in its compounds except in the metal hybrids.
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Cu + 2H2SO4 produces CuSO4 and SO2 with the formation of ______.
Cu + 2H2SO4 produces CuSO4 and SO2 with the formation of ______.
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The halogens always have an oxidation number of ______ in their compounds unless bonded to a more electronegative atom.
The halogens always have an oxidation number of ______ in their compounds unless bonded to a more electronegative atom.
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When an element is oxidised, its oxidation number ______, indicating an increase in its oxidation state.
When an element is oxidised, its oxidation number ______, indicating an increase in its oxidation state.
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Sulfuric acid acts as the ______ agent in oxidation-reduction reactions.
Sulfuric acid acts as the ______ agent in oxidation-reduction reactions.
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The oxidation number of sulphur in Na2S2O3 is ______.
The oxidation number of sulphur in Na2S2O3 is ______.
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In the reaction of potassium bromide with chlorine water, the solution turns a yellow/orange color due to the formation of ______.
In the reaction of potassium bromide with chlorine water, the solution turns a yellow/orange color due to the formation of ______.
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Chlorine displaces bromine from a solution of a ______ salt.
Chlorine displaces bromine from a solution of a ______ salt.
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The addition of barium chloride solution to the test tube results in a ______ precipitate when sulfate ions are present.
The addition of barium chloride solution to the test tube results in a ______ precipitate when sulfate ions are present.
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Bromine can oxidise iodide ions, confirming that it is a ______ agent.
Bromine can oxidise iodide ions, confirming that it is a ______ agent.
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When chlorine water is added to sodium sulfite solution, no ______ change is observed initially.
When chlorine water is added to sodium sulfite solution, no ______ change is observed initially.
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The reddish-brown color in potassium iodide solution is due to the formation of ______.
The reddish-brown color in potassium iodide solution is due to the formation of ______.
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The greenish-brown precipitate observed confirms the presence of ______ ions.
The greenish-brown precipitate observed confirms the presence of ______ ions.
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When magnesium is placed in copper sulfate solution, it displaces ______ from the solution.
When magnesium is placed in copper sulfate solution, it displaces ______ from the solution.
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The oxidation half-equation for iron(II) sulfate is ______ -> Fe3+ + 2e-.
The oxidation half-equation for iron(II) sulfate is ______ -> Fe3+ + 2e-.
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The reaction involving zinc and copper sulfate demonstrates that zinc has a greater tendency to ______ electrons than copper.
The reaction involving zinc and copper sulfate demonstrates that zinc has a greater tendency to ______ electrons than copper.
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In the redox reaction, MnO4- is reduced to Mn2+ which involves the gain of ______ electrons.
In the redox reaction, MnO4- is reduced to Mn2+ which involves the gain of ______ electrons.
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The process of balancing the redox equation ensures that the number of ______ gained equals the number of electrons lost.
The process of balancing the redox equation ensures that the number of ______ gained equals the number of electrons lost.
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During the experiment, no apparent change occurs when chlorine water is added to the iron(II) sulfate solution until ______ is added.
During the experiment, no apparent change occurs when chlorine water is added to the iron(II) sulfate solution until ______ is added.
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The blue color of copper sulfate solution becomes lighter because magnesium displaces Cu2+ ions, leading to a ______ solution.
The blue color of copper sulfate solution becomes lighter because magnesium displaces Cu2+ ions, leading to a ______ solution.
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Study Notes
Oxidation and Reduction
- Oxidation: Loss of electrons
- Reduction: Gain of electrons
- OILRIG: Oxidation Is Loss, Reduction Is Gain
- Oxidation and reduction always occur together
- Redox reactions involve both oxidation and reduction
Oxidising Agents
- A substance that brings about oxidation in other substances
- Always reduced in the process
Reducing Agents
- A substance that brings about reduction in other substances
- Always oxidized in the process
Examples of Redox Reactions
- 2Mg + O2 → 2MgO (Magnesium oxidized, oxygen reduced)
- Cu2+ + H2 → Cu + H2O (Cu2+ reduced, H2 oxidized)
- 2Na + Cl2 → 2NaCl (Sodium oxidized, chlorine reduced)
Oxidation Numbers
- The charge an atom has or appears to have when electrons are distributed
- Important in tracking electrons during chemical reactions involving covalent compounds
Rules for Assigning Oxidation Numbers
- Uncombined elements have an oxidation number of 0
- Ions have oxidation numbers equal to their charge
- The sum of oxidation numbers in a compound is zero
- Oxygen usually has an oxidation number of -2 (except in peroxide compounds and OF2)
- Hydrogen usually has an oxidation number of +1 (except in metal hydrides)
- Halogens usually have an oxidation number of -1
Oxidation and Reduction in Terms of Oxidation Numbers
- Oxidation: Increase in oxidation number
- Reduction: Decrease in oxidation number
Examples of Oxidation and Reduction in Reactions
- Cu + 2H2SO4 → CuSO4 + SO2 + 2H2O (Cu oxidized; H2SO4 reduced)
- Chlorine reacts with potassium bromide solution (or potassium iodide) which demonstrates the oxidative ability of chlorine (or bromine)
The Oxidising Ability of the Halogens
- Chlorine displaces bromine from a solution of a bromide salt
- Chlorine displaces iodine from a solution of an iodide salt
- Bromine displaces iodine from a solution of an iodide salt
- A halogen will oxidise the ions of any other halogen below it in the group
Displacement Reactions of Metals
- Zinc displaces copper from copper sulfate solution, forcing copper atoms to accept electrons from zinc
Balancing Redox Equations
- A step-by-step method to balance redox reactions using oxidation numbers. This method is shown in the example of balancing MnO4- + Fe2+ + H+ → Mn2+ + Fe3+ + H2O.
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Description
Test your understanding of oxidation and reduction in chemistry with this quiz. Explore important concepts like oxidizing and reducing agents, as well as oxidation numbers. Perfect for students studying redox reactions and their applications.
