Predict products when water also supplies ions.
| English | Chinese |
|---|---|
| aqueous | 水溶液的 |
| concentrated | 浓的 |
| dilute | 稀的 |
| inert electrode | 惰性电极 |
Try each question before opening its hint or answer. Use paper for calculations and diagrams.
Why does aqueous NaCl give hydrogen instead of sodium at the cathode?
List all ions before choosing products. Check whether the question says molten, dilute or concentrated.
Sodium is more reactive than hydrogen; hydrogen is discharged and Na⁺ remains in solution.
Predict both products from concentrated aqueous KBr using inert electrodes.
Include the ions supplied by water as well as the salt.
Cathode: hydrogen. Anode: bromine.
Predict both products from dilute sulfuric acid and give the expected gas volume ratio.
Use the overall decomposition of water to determine the gas ratio.
Hydrogen at cathode, oxygen at anode; H₂:O₂ = 2:1 at the same conditions.
Use Lesson 3 in your worksheet for written practice. Your teacher will discuss those answers in class.
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.
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.