Electrochemistry Concepts Quiz

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Questions and Answers

What is the primary function of an electrode in an electrochemical cell?

To act as a source of electrolyte

To provide a pathway for the flow of electrons (correct)

To regulate temperature within the cell

To initiate chemical reactions with the electrolyte

What is the significance of the electrochemical series?

It ranks metals based on their tendency to lose electrons (correct)

It predicts the reactions in an electrolytic cell

It measures conductivity of various metals

It shows metals arranged by their melting points

What distinguishes inert electrodes from active electrodes?

Inert electrodes do not react with the electrolyte, active do (correct)

Inert electrodes produce electricity, active do not

Inert electrodes can conduct heat, while active cannot

Inert electrodes undergo oxidation in reactions, active do not

What is the outcome at the anode during electrolysis?

Oxidation occurs with an electron loss Signup and view all the answers

What color change occurs during the electrolysis of copper dichromate?

Yellow at the anode and blue at the cathode Signup and view all the answers

What is the role of the electrolyte in electrolysis?

To conduct electricity in aqueous solution or molten state Signup and view all the answers

What is the mnemonic device used to remember the flow of electrons during electrolysis?

CatNAP - Cathode Negative Anode Positive Signup and view all the answers

What happens during a displacement experiment?

A more reactive metal displaces a less reactive one Signup and view all the answers

Which of the following best defines electrolysis?

The breakdown of a substance through electric current Signup and view all the answers

What materials are typical for inert electrodes?

Graphite and Platinum Signup and view all the answers

What does the colour change observed at the cathode during the electrolysis of copper dichromate signify?

It indicates the reduction of Cu²⁺ ions Signup and view all the answers

Why is a more reactive metal able to displace another metal from its salt solution?

Because it has a greater tendency to lose electrons Signup and view all the answers

What is the primary purpose of electroplating?

To apply a layer of one metal onto another Signup and view all the answers

Which apparatus is commonly used for the electrolysis of acidified water?

Hoffman Voltameter Signup and view all the answers

What happens to the mass of the anode in the electrolysis of copper(II) sulfate solution?

Decreases in mass Signup and view all the answers

What is produced at the cathode during the electrolysis of acidified water?

Hydrogen gas Signup and view all the answers

What describes the reaction ratio of the gases produced during the electrolysis of water?

2:1 ratio of hydrogen to oxygen Signup and view all the answers

What prevents sulfate ions from reacting during the electrolysis of acidified water?

They require a higher voltage to react Signup and view all the answers

Which half equation represents the cathode reaction during the electrolysis of KI?

2H₂O + 2e⁻ → H₂ + 2OH⁻ Signup and view all the answers

What is the colour observed at the anode during the electrolysis of potassium iodide (KI)?

Red/Brown due to iodine Signup and view all the answers

Study Notes

Electrochemical Cell Fundamentals

Electrodes serve as conductors connected to the positive or negative terminals of a battery, facilitating the flow of electric current.
The electrochemical series ranks metals by their propensity to lose electrons, influencing reactions in electrochemical cells.

Types of Electrodes

Inert electrodes, crafted from materials like graphite or platinum, do not engage in reactions with the electrolyte.
Active electrodes participate in reactions with the electrolyte, affecting the electrochemical processes.

Electrolysis Process

Oxidation occurs at the anode, while reduction takes place at the cathode during electrolysis.
The electrolyte, essential for electrolysis, conducts electricity when dissolved in water or molten.

Displacement and Electrolysis Observations

A displacement experiment demonstrates that a more reactive metal can displace a less reactive metal from its salt solution.
A color change during the electrolysis of copper dichromate indicates Cu²⁺ ions moving to the cathode for reduction (blue color), while CuCr₂O₇²⁻ anions move to the anode (yellow color).

Mnemonics and Indicators

The mnemonic "CatNAP" helps recall the flow of electrons: Cathode Negative, Anode Positive.
A universal indicator in the electrolysis of aqueous sodium sulfate shows pH changes near electrodes, crucial for understanding the process.

Definition and Purpose of Electrolysis

Electrolysis involves the breakdown of a substance using an electric current, either in an aqueous solution or molten state.
Electroplating applies electrolysis to deposit a layer of metal onto another surface.

Apparatus and Reactions

A Hoffman voltameter is typically used to perform electrolysis on acidified water.
Reactions in electrolysis of acidified water lead to the production of hydrogen at the cathode and oxygen at the anode, in a 2:1 volume ratio.

Reactions Involving Copper Sulfate and Metals

Magnesium and zinc displace copper from copper sulfate:
- Mg + CuSO₄ → MgSO₄ + Cu
- Zn + CuSO₄ → ZnSO₄ + Cu

Mass Changes and Ion Behavior

During electrolysis of copper(II) sulfate:
- The mass at the anode decreases as copper ions are oxidized into solution.
- The mass at the cathode increases as Cu²⁺ ions are reduced and deposited as solid copper.
Sulfate ions remain unreacted during acidified water electrolysis due to requiring higher voltage for reaction.

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Description

Test your knowledge of fundamental electrochemistry concepts, including the roles of electrodes and the significance of the electrochemical series. This quiz covers the differences between inert and active electrodes, helping you better understand their functions in electrochemical cells.