Question 1
Which electrode attracts anions during electrolysis? Give its name and sign.
Need a hint for Question 1?
Give the ion symbols, then match each charge to the opposite electrode.
Check Question 1
The positive anode.
STUDENT SPACE · TOPIC 1
Charge flow and molten electrolysis
Explain charge flow and predict products from molten binary compounds.
The essentials
- Metals and graphite conduct through mobile electrons. Electrolytes conduct through mobile ions.
- Electrolysis decomposes an ionic compound, molten or in aqueous solution, by passing an electric current.
- Cations move towards the negative cathode. Anions move towards the positive anode.
Key vocabulary
| English | Chinese |
|---|---|
| electrolysis | 电解 |
| electrolyte | 电解质 |
| anode | 阳极 |
| cathode | 阴极 |
Quick practice
Try each question before opening its hint or answer. Use paper for calculations and diagrams.
Question 2
Predict the cathode and anode products from molten NaCl.
Need a hint for Question 2?
Match each ion to the oppositely charged electrode.
Check Question 2
Cathode: sodium. Anode: chlorine.
Question 3
Explain how charge crosses the electrolyte and the external wires.
Need a hint for Question 3?
Compare charge carriers in a liquid electrolyte and a metal wire.
Check Question 3
Mobile ions carry charge in the electrolyte; electrons carry charge in the wires.
Use Lesson 1 in your worksheet for written practice. Your teacher will discuss those answers in class.
Electrolytic cell · a power supply drives change
Electrons carry charge in metal wires. Ions carry charge in the electrolyte.
Predict first: Name both products and write the half-equations. What changes if you change the anode material?
Schematic teaching model: motion and particle numbers are illustrative. Moving anions do not necessarily discharge: electrode material and competing ions determine products.
PREDICT · TRY · EXPLAIN · 3–5 MINUTES
Inside an electrolytic cell
Predict the product at each electrode. Run the cell, then explain where ions and electrons move.
Molten PbBr₂; inert electrodes. This is a model, not a home experiment.
DC power supply
− supplies electrons to cathode · + removes electrons from anode
− supplies electrons to cathode · + removes electrons from anode
− Cathode
Reduction+ Anode
Oxidation
Reduction+ Anode
Oxidation
← Pb²⁺ cationsBr⁻ anions →
Electrons travel through wires and electrodes. Ions carry charge through the electrolyte. Movement towards an electrode does not mean an ion must be discharged there.