Electrochemistry: MCQ 3

Podcast Beta

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What type of ions are attracted to the anode?

Neutral molecules

Cations

Electrons

Anions (correct)

What happens to the active anode electrode during electrolysis?

It becomes a cathode

It produces oxygen

It remains unchanged

It gradually dissolves (correct)

What is the purpose of the universal indicator in the electrolysis of aqueous sodium sulfate?

To identify the anode and cathode

To catalyze the electrolysis reaction

To measure the voltage of the battery

To indicate the pH of the solution (correct)

What is the result of oxidation at the anode during the electrolysis of acidified water?

Oxygen gas is released Signup and view all the answers

What occurs at the anode during the electrolysis of Copper(II) sulphate solution using Copper Electrodes?

Oxidation of copper occurs releasing Cu²⁺ ions Signup and view all the answers

What type of electrodes are used in the electrolysis of copper(II) sulfate?

Active electrodes Signup and view all the answers

What is the purpose of electroplating?

To coat an inexpensive metal with a more expensive metal Signup and view all the answers

What is the result of the electrolysis of impure copper using an impure copper anode and a pure copper cathode?

Pure copper is deposited at the cathode Signup and view all the answers

What is the function of the dc power supply in electrolysis?

To provide the energy needed for electrolysis to occur Signup and view all the answers

What is the result of reduction at the cathode during electrolysis?

Copper ions are reduced to form solid copper Signup and view all the answers

What is the primary purpose of the electrochemical series?

To arrange metals in order of their tendency to lose electrons Signup and view all the answers

Which of the following metals will displace iron from a solution of its salt?

Zinc Signup and view all the answers

What is the role of an electrolyte in electrolysis?

To conduct electricity when dissolved in water or molten Signup and view all the answers

What happens to magnesium when it is dipped into copper sulfate solution?

It displaces the copper ions from the solution Signup and view all the answers

What is the outcome of the reaction between magnesium and copper sulfate solution?

Magnesium is oxidized and copper is reduced Signup and view all the answers

Study Notes

The Electrochemical Series

The electrochemical series is a table that shows metals arranged in order of their tendency to lose electrons.
The more readily a metal loses electrons, the more reactive it is.
Potassium is at the top of the electrochemical series, and gold is at the bottom.
A metal will displace another metal below it in the electrochemical series from a solution of its salt.

Displacement Reactions

Magnesium ribbon dipped in copper sulfate solution displaces copper ions from the solution.
The displaced copper then coats the magnesium ribbon.
Zinc becomes covered in copper metal because zinc is higher in the electrochemical series and displaces copper.

Electrolysis

Electrolysis is the breaking up of a substance due to an electric current passing through it in an aqueous solution or when molten.
Electrolysis requires electrodes and an electrolyte.
An electrolyte is a substance that conducts electricity when dissolved in water or when molten.
Electrolytes themselves become chemically changed during electrolysis.

Electrodes

An electrode is a conductor connected to the positive or negative end of a battery.
There are two types of electrodes: inert electrodes (e.g., graphite and platinum) and active electrodes (e.g., copper).
An active anode electrode gradually dissolves as electricity is passed through the electrolyte.

Anode and Cathode

Oxidation occurs at the anode (OIL), and reduction occurs at the cathode (RIG).
Anions are attracted to the anode, while cations are attracted to the cathode.

Experiment to Demonstrate Ionic Movement

Copper dichromate solution breaks up into Cu²⁺ cations and Cr₂O₇²⁻ anions during electrolysis.
Cu²⁺ cations are attracted to the cathode, and Cr₂O₇²⁻ anions are attracted to the anode.

Electrolysis of Aqueous Sodium Sulfate

Sodium sulfate solution and universal indicator are used.
At the anode, O₂ gas is released, and H⁺ ions are present.
At the cathode, OH⁻ ions are released, causing the indicator to turn blue.

Electrolysis of Aqueous Potassium Iodide

Potassium iodide solution and phenolphthalein indicator are used.
At the anode, I₂ is formed, resulting in a brown color.
At the cathode, K⁺ ions are reduced.

Electrolysis of Acidified Water

This is carried out using a Hoffman Voltameter.
Water breaks up into H⁺ and OH⁻ ions.
H⁺ ions are reduced at the cathode, resulting in H₂ gas.
OH⁻ ions are oxidized at the anode, resulting in O₂ gas.

Electrolysis of Copper (II) Sulfate Solution

Copper electrodes are used.
At the anode, copper is oxidized, and Cu²⁺ ions are released into solution.
At the cathode, Cu²⁺ ions are reduced, and solid copper is formed.

Electroplating

This involves coating one inexpensive metal with another more expensive metal using electrolysis.
Examples include coating nickel cutlery with silver and chrome plating of steel.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Learn about the electrochemical series, metal reactivity, and displacement of metals from salt solutions. Understand how metals are arranged in the series and how one metal can displace another.