Oxydoréduction et demi-équations Practice Quiz (11 questions)

Question 1

1. How is a redox couple formed and conventionally written?

An oxidant and reductant of different elements, written oxidant/reductant

A reductant and oxidant of the same element, written reductant/oxidant

An oxidant and reductant of the same element, written oxidant/reductant

Two oxidants of the same element, written oxidant/reductant

Explanation

A redox couple joins an oxidant and its conjugate reductant derived from the same element, with the oxidant written first. Different elements do not form one couple, reversing the order miswrites it, and two oxidants do not make the required pair.

Answer

An oxidant and reductant of the same element, written oxidant/reductant

Question 2

2. In a reaction, species X gains electrons and becomes its conjugate reduced form; what role does X play?

A spectator species

A reductant

A conjugate reduced form

An oxidant

Explanation

An oxidant captures electrons and is transformed into its conjugate reductant. Calling X a reductant confuses electron gain with donation, while the conjugate reduced form is the product and a spectator does not account for this electron transfer.

Answer

An oxidant

Question 3

3. During electron transfer, species Y releases electrons and becomes its conjugate oxidized form; what role does Y play?

A reductant

An oxidant

A conjugate oxidized form

A redox couple

Explanation

A reductant donates electrons and is transformed into its conjugate oxidant. An oxidant captures electrons, the conjugate oxidized form is the product, and a redox couple names the paired forms rather than Y's role.

Answer

A reductant

Question 4

4. What does a single electronic half-equation represent?

Electron transfer for one redox couple

Electron transfer for two redox couples

A complete reaction between two redox couples

A physical change involving one chemical species

Explanation

An electronic half-equation represents electron transfer for one oxidant–reductant couple. Combining two couples describes a broader reaction, while a physical state change does not express electron transfer.

Answer

Electron transfer for one redox couple

Question 5

5. For a couple whose oxidant captures three electrons to become its reductant, which half-equation matches the general model?

\text{Ox} \rightarrow \text{Red} + 3e^-

\text{Red} + 3e^- \rightarrow \text{Ox}

3\text{Ox} + e^- \rightarrow \text{Red}

\text{Ox} + 3e^- \rightarrow \text{Red}

Explanation

The oxidant captures the specified three electrons, so electrons appear with the oxidant on the left and the reductant appears on the right. Putting electrons on the product side depicts donation, multiplying Ox changes the electron count, and reversing Ox and Red reverses the transformation.

Answer

$$\text{Ox} + 3e^- \rightarrow \text{Red}$$

Question 6

6. A student writes the reduction half-equation for an ion $M^{3+}$ becoming neutral metal $M$ . After balancing the element, which adjustment balances the charge?

Add three electrons to the reactant side

Add three electrons to the product side

Add one electron to the reactant side

Add three protons to the reactant side

Explanation

The element is already balanced, and the oxidant side has a charge of $+3$ , so three electrons are added there to balance charge. Putting electrons on the product side worsens the imbalance, while protons do not balance charge in this procedure.

Answer

Add three electrons to the reactant side

Question 7

7. When balancing the reduction half-equation for $Cu^{2+}$ becoming solid copper, which expression correctly conserves both copper atoms and charge?

Cu^{2+} \rightarrow Cu

Cu^{2+} \rightarrow Cu + 2e^-

Cu^{2+} + 2e^- \rightarrow Cu

Cu^{2+} + e^- \rightarrow Cu

Explanation

The copper atoms are already balanced, and two electrons on the oxidant side reduce the charge from $+2$ to zero. Omitting electrons or using one leaves a charge imbalance, while placing them on the product side increases it.

Answer

$$Cu^{2+} + 2e^- \rightarrow Cu$$

Question 8

8. Which pair of reacting species characterizes an oxidation-reduction reaction involving two different redox couples?

The reductants from two different couples

The oxidants from two different couples

An oxidant and its conjugate reductant from one couple

The oxidant from one couple and the reductant from another

Explanation

A redox reaction involves an oxidant from one couple reacting with a reductant from another, and the resulting equation must be adjusted. Pairing two oxidants or two reductants misses the electron transfer between oxidizing and reducing species.

Answer

The oxidant from one couple and the reductant from another

Question 9

9. Two half-equations in a proposed reaction transfer $2$ electrons and $3$ electrons, respectively. To equalize the transferred electrons, what multipliers should be applied to the $2$ -electron and $3$ -electron half-equations, in that order?

2

and

3

3

and

2

1

and

2

2

and

2

Explanation

Each half-equation is multiplied by the electron count in the other one, giving $3$ for the $2$ -electron equation and $2$ for the $3$ -electron equation; both then transfer $6$ electrons. Using each equation's own count or the difference does not equalize the transfer.

Answer

$$3$$ and $$2$$

Question 10

10. In a redox reaction, species X gains electrons while species Y loses electrons. What happens to X and Y, respectively?

X is oxidized, and Y is reduced

X and Y are both oxidized

X and Y are both reduced

X is reduced, and Y is oxidized

Explanation

Gaining electrons reduces X, while losing electrons oxidizes Y. Reversing gain and loss swaps the outcomes; treating both as reduced or both as oxidized ignores that electron transfer has opposite effects on the two species.

Answer

X is reduced, and Y is oxidized

Question 11

11. In the reaction between silver ions and solid copper, which species acts as the reducing agent and what happens to it?

Silver ions are the reducing agent and are oxidized

Solid copper is the reducing agent and is oxidized

Silver ions are the reducing agent and are reduced

Solid copper is the reducing agent and is reduced

Explanation

Solid copper donates electrons, so it is the reducing agent and is oxidized. Silver ions are the oxidizing agent and are reduced; saying copper is reduced reverses the effect of electron loss, while assigning the reducing role to silver ions confuses the two agents.

Answer

Solid copper is the reducing agent and is oxidized

Oxydoréduction et demi-équations Practice Quiz (11 questions)

All questions and answers

1. How is a redox couple formed and conventionally written?

2. In a reaction, species X gains electrons and becomes its conjugate reduced form; what role does X play?

3. During electron transfer, species Y releases electrons and becomes its conjugate oxidized form; what role does Y play?

4. What does a single electronic half-equation represent?

5. For a couple whose oxidant captures three electrons to become its reductant, which half-equation matches the general model?

6. A student writes the reduction half-equation for an ion $M^{3+}$ becoming neutral metal $M$ . After balancing the element, which adjustment balances the charge?

7. When balancing the reduction half-equation for $Cu^{2+}$ becoming solid copper, which expression correctly conserves both copper atoms and charge?

8. Which pair of reacting species characterizes an oxidation-reduction reaction involving two different redox couples?

9. Two half-equations in a proposed reaction transfer $2$ electrons and $3$ electrons, respectively. To equalize the transferred electrons, what multipliers should be applied to the $2$ -electron and $3$ -electron half-equations, in that order?

10. In a redox reaction, species X gains electrons while species Y loses electrons. What happens to X and Y, respectively?

11. In the reaction between silver ions and solid copper, which species acts as the reducing agent and what happens to it?

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Read the study guide

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Oxydoréduction et demi-équations Practice Quiz (11 questions)

All questions and answers

1. How is a redox couple formed and conventionally written?

2. In a reaction, species X gains electrons and becomes its conjugate reduced form; what role does X play?

3. During electron transfer, species Y releases electrons and becomes its conjugate oxidized form; what role does Y play?

4. What does a single electronic half-equation represent?

5. For a couple whose oxidant captures three electrons to become its reductant, which half-equation matches the general model?

6. A student writes the reduction half-equation for an ion M3+M^{3+}M3+ becoming neutral metal MMM. After balancing the element, which adjustment balances the charge?

7. When balancing the reduction half-equation for Cu2+Cu^{2+}Cu2+ becoming solid copper, which expression correctly conserves both copper atoms and charge?

8. Which pair of reacting species characterizes an oxidation-reduction reaction involving two different redox couples?

9. Two half-equations in a proposed reaction transfer 222 electrons and 333 electrons, respectively. To equalize the transferred electrons, what multipliers should be applied to the 222-electron and 333-electron half-equations, in that order?

10. In a redox reaction, species X gains electrons while species Y loses electrons. What happens to X and Y, respectively?

11. In the reaction between silver ions and solid copper, which species acts as the reducing agent and what happens to it?

Study with flashcards

Read the study guide

Related classes

Weighted Averages of Points

Year 9 Science Revision Skills

Vector Algebra and Components

Chromosomes and Molecular Biology

Factorising and Solving Quadratics

Ocean Dynamics and Climate

Make your own practice quizzes

6. A student writes the reduction half-equation for an ion $M^{3+}$ becoming neutral metal $M$ . After balancing the element, which adjustment balances the charge?

7. When balancing the reduction half-equation for $Cu^{2+}$ becoming solid copper, which expression correctly conserves both copper atoms and charge?

9. Two half-equations in a proposed reaction transfer $2$ electrons and $3$ electrons, respectively. To equalize the transferred electrons, what multipliers should be applied to the $2$ -electron and $3$ -electron half-equations, in that order?