Electrolysis of specific substances
12 flashcards to master Electrolysis of specific substances
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Define electrolysis.
Electrolysis is the breakdown of an ionic compound, in molten or aqueous state, by the passage of electricity.
Why is graphite used as an electrode in electrolysis?
Graphite is used because it is inert and conducts electricity. Inert means it doesn't react with the electrolyte or the products of electrolysis. It allows electrons to flow.
Write the half-equation for the formation of hydrogen gas at the cathode.
2H⁺ + 2e⁻ → H₂. This shows that hydrogen ions (H⁺) gain two electrons to form hydrogen gas (H₂).
What particles carry the electric current through the wires in an electrolytic cell?
Electrons carry the electric current through the wires. They flow from the power supply to the cathode and from the anode back to the power supply.
What particles carry the electric current through the electrolyte in an electrolytic cell?
Ions carry the electric current through the electrolyte. Positive ions (cations) move towards the cathode, and negative ions (anions) move towards the anode.
During the electrolysis of brine (concentrated NaCl solution), which gases are produced at the anode and cathode?
Anode: Chlorine; Cathode: Hydrogen. The sodium ions and hydroxide ions remain in solution, creating sodium hydroxide.
What is the chemical formula of the compound that is electrolyzed to extract aluminum?
Aluminium oxide (Al₂O₃). This is also known as alumina.
Why is cryolite mixed with aluminum oxide during the electrolysis of aluminum?
Cryolite serves as a solvent, lowers the operating temperature (reducing energy costs), and increases the conductivity of the electrolyte. This makes the process more efficient and economical.
Why do the carbon anodes need to be replaced periodically during the electrolysis of aluminum oxide?
The carbon reacts with the oxygen produced at the anode and forms carbon dioxide (CO₂). This gradually erodes the anode.
Write the balanced chemical equation for the overall reaction in a hydrogen-oxygen fuel cell.
2H₂ + O₂ → 2H₂O. Hydrogen gas reacts with oxygen gas to produce water.
Give two advantages of using hydrogen-oxygen fuel cells compared to gasoline/petrol engines in vehicles.
No carbon dioxide is evolved, reducing greenhouse gas emissions, and hydrogen-oxygen fuel cells are more efficient at converting chemical energy into mechanical energy.
What happens to the colour of the electrolyte during the electrolysis of copper(II) sulfate using inert electrodes?
The electrolyte gets lighter/fades/less blue. This is because the concentration of Cu²⁺ ions in the solution decreases as copper is deposited at the cathode.
Key Questions: Electrolysis of specific substances
Define electrolysis.
Electrolysis is the breakdown of an ionic compound, in molten or aqueous state, by the passage of electricity.
About Electrolysis of specific substances (4.2)
These 12 flashcards cover everything you need to know about Electrolysis of specific substances for your Cambridge IGCSE Chemistry (0620) exam. Each card is designed based on the official syllabus requirements.
What You'll Learn
- 1 Definitions - Key terms and their precise meanings that examiners expect
- 4 Key Concepts - Core ideas and principles from the 0620 syllabus
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After mastering Electrolysis of specific substances, explore these related topics:
- 4.1 Electrolysis - 12 flashcards
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