4.1

Electrolysis

12 flashcards to master Electrolysis

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Definition Flip

Define electrolysis.

Answer Flip

Electrolysis is the decomposition of an ionic compound, when molten or in aqueous solution, by the passage of an electric current.

Example: passing electricity through molten lead(II) bromide breaks it down into lead and bromine.
Key Concept Flip

In an electrolytic cell, what is the anode and what is its charge?

Answer Flip

The anode is the positive electrode in an electrolytic cell. It's where oxidation (loss of electrons) occurs.

Example: in the electrolysis of NaCl, chloride ions are oxidised at the anode.
Key Concept Flip

In an electrolytic cell, what is the cathode and what is its charge?

Answer Flip

The cathode is the negative electrode in an electrolytic cell. It's where reduction (gain of electrons) occurs.

Example: in the electrolysis of NaCl, sodium ions are reduced at the cathode.
Definition Flip

What is the electrolyte in electrolysis?

Answer Flip

The electrolyte is the molten or aqueous substance that undergoes electrolysis. It contains ions that are free to move and conduct electricity. An example is molten lead(II) bromide or aqueous sodium chloride.

Key Concept Flip

Describe the movement of charge during electrolysis in the external circuit.

Answer Flip

Electrons move in the external circuit from the power supply to the cathode and from the anode back to the power supply. This flow of electrons constitutes the electric current. These electrons are gained or lost by ions at the electrodes.

Key Concept Flip

Describe the movement of charge during electrolysis within the electrolyte.

Answer Flip

Ions move in the electrolyte. Positive ions (cations) move towards the cathode, and negative ions (anions) move towards the anode. This movement of ions carries the charge through the electrolyte.

Key Concept Flip

What are the products of electrolysis of molten lead(II) bromide using inert electrodes?

Answer Flip

At the cathode (negative electrode), molten lead is formed. At the anode (positive electrode), bromine gas is formed. Observation: Brown fumes are produced at the anode.

Key Concept Flip

What are the products of electrolysis of concentrated aqueous sodium chloride using inert electrodes?

Answer Flip

At the cathode (negative electrode), hydrogen gas is formed. At the anode (positive electrode), chlorine gas is formed. Observation: Bubbles of gas produced at both electrodes, pungent smell at the anode. The remaining solution is sodium hydroxide.

Key Concept Flip

What are the products of electrolysis of dilute sulfuric acid using inert electrodes?

Answer Flip

At the cathode (negative electrode), hydrogen gas is formed. At the anode (positive electrode), oxygen gas is formed. Observation: Bubbles of gas are produced at both electrodes. More hydrogen is produced than oxygen.

Key Concept Flip

What type of substance is formed at the cathode during electrolysis?

Answer Flip

Metals or hydrogen are formed at the cathode during electrolysis. This is because positive metal ions or H+ ions are attracted to the negative electrode and gain electrons (are reduced).

Key Concept Flip

What type of substance is formed at the anode during electrolysis?

Answer Flip

Non-metals (other than hydrogen) are formed at the anode during electrolysis. This is because negative non-metal ions are attracted to the positive electrode and lose electrons (are oxidized).

Definition Flip

What is electroplating, and why is it done?

Answer Flip

Electroplating is the process of coating a metal object with a thin layer of another metal using electrolysis. It is done to improve the appearance of the object and to increase its resistance to corrosion.

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3.3 Calculations 4.2 Electrolysis of specific substances

Key Questions: Electrolysis

Define electrolysis.

Electrolysis is the decomposition of an ionic compound, when molten or in aqueous solution, by the passage of an electric current.

Example: passing electricity through molten lead(II) bromide breaks it down into lead and bromine.
What is the electrolyte in electrolysis?

The electrolyte is the molten or aqueous substance that undergoes electrolysis. It contains ions that are free to move and conduct electricity. An example is molten lead(II) bromide or aqueous sodium chloride.

What is electroplating, and why is it done?

Electroplating is the process of coating a metal object with a thin layer of another metal using electrolysis. It is done to improve the appearance of the object and to increase its resistance to corrosion.

About Electrolysis (4.1)

These 12 flashcards cover everything you need to know about Electrolysis for your Cambridge IGCSE Chemistry (0620) exam. Each card is designed based on the official syllabus requirements.

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