Electrolysis: mobile ions move to oppositely charged electrodes
| English | 中文 | Pinyin |
|---|---|---|
| electrolyte/ɪˈlektrəlaɪt/ | 电解质 | diàn jiě zhì |
| cathode/ˈkæθəʊd/ | 阴极 | yīn jí |
What would explain this observation?
- An ionic solid does not conduct through fixed ions, but its melt can. Connecting a direct-current supply to that liquid can cause different products at its two electrodes.
- Start with a prediction. State the quantities or features you would compare, then decide what evidence could distinguish two explanations.
Build the model
- An electrolyte 电解质 is a liquid or solution containing mobile ions that can conduct electricity. Melting an ionic compound or dissolving a suitable ionic compound frees ions to move. In electrolysis, the negative electrode is the cathode 阴极 and attracts positive ions; the positive electrode is the anode and attracts negative ions. Discharged ions form products at the electrode surfaces.
- electrolyte: A liquid or solution conducting charge through mobile ions; cathode: The negative electrode in the powered electrolysis model, where reduction occurs.
Where do positive ions move in a powered electrolytic cell?
Charge travels through the electrolyte by moving ions and through the external circuit by electrons. Positive ions are not positive electrons, and solid salt ions do not become mobile simply because a wire touches the solid. Electrolysis uses electrical energy to drive chemical change. The polarity names here apply to an externally powered electrolytic cell, not a blanket rule for every electrochemical cell.
Match each technical term to its precise meaning.
Use the definitions to distinguish related quantities and processes.
Choose evidence that can test it
- Charge travels through the electrolyte by moving ions and through the external circuit by electrons. Positive ions are not positive electrons, and solid salt ions do not become mobile simply because a wire touches the solid. Electrolysis uses electrical energy to drive chemical change. The polarity names here apply to an externally powered electrolytic cell, not a blanket rule for every electrochemical cell.
- Draw a labelled direct-current supply, two separated electrodes and the electrolyte. Mark supply polarity, electrode identity and arrows for each ion type. Actual school work uses approved low-voltage equipment and solutions, with electrodes held apart to prevent short circuits. Record products and observations at the named electrode instead of merely saying bubbles occurred somewhere.
Which two habits make the investigation or model in this case more defensible?
Draw a labelled direct-current supply, two separated electrodes and the electrolyte. Mark supply polarity, electrode identity and arrows for each ion type. Actual school work uses approved low-voltage equipment and solutions, with electrodes held apart to prevent short circuits. Record products and observations at the named electrode instead of merely saying bubbles occurred somewhere.
Work from known quantities
- State the known values and their units. Choose the relation because its assumptions fit this case, then rearrange before substitution.
- Known: a labelled model has electrode A connected to the negative supply terminal and B to the positive. Cu²⁺ moves towards A, while Cl⁻ moves towards B. A is the cathode and B the anode. In a particle-count illustration, five Cu²⁺ and ten Cl⁻ have balanced total charge +10−10=0; equal ion counts are not required for neutrality.
How many Cl⁻ ions balance the total charge of seven Cu²⁺ ions? Use the same sequence: known quantities → model → relation → substitution → unit and interpretation.
How many Cl⁻ ions balance the total charge of seven Cu²⁺ ions?
The result is 14 ions. Known: a labelled model has electrode A connected to the negative supply terminal and B to the positive. Cu²⁺ moves towards A, while Cl⁻ moves towards B. A is the cathode and B the anode. In a particle-count illustration, five Cu²⁺ and ten Cl⁻ have balanced total charge +10−10=0; equal ion counts are not required for neutrality.
Check the conclusion and its limits
- The electrode signs attract ions but do not imply that every positive ion forms its metal in an aqueous solution; water-derived species can compete. That product-selection rule is separate. Higher-only half equations are also separate from this common-tier movement and apparatus model.
- Return to the original observation. Explain what the result supports, which conditions it assumes, and one way to test a competing explanation.
Electrons moving through the liquid are the only charge carriers in an ionic electrolyte. This claim is false: The electrode signs attract ions but do not imply that every positive ion forms its metal in an aqueous solution; water-derived species can compete. That product-selection rule is separate. Higher-only half equations are also separate from this common-tier movement and apparatus model.
Electrolysis: mobile ions move to oppositely charged electrodes: Charge travels through the electrolyte by moving ions and through the external circuit by electrons. Positive ions are not positive electrons, and solid salt ions do not become mobile simply because a wire touches the solid. Electrolysis uses electrical energy to drive chemical change. The polarity names here apply to an externally powered electrolytic cell, not a blanket rule for every electrochemical cell.
Electrons moving through the liquid are the only charge carriers in an ionic electrolyte.
The electrode signs attract ions but do not imply that every positive ion forms its metal in an aqueous solution; water-derived species can compete. That product-selection rule is separate. Higher-only half equations are also separate from this common-tier movement and apparatus model.
A liquid or solution conducting charge through mobile ions: write the technical term.
electrolyte means A liquid or solution conducting charge through mobile ions.