Electrolysis - Aqueous Solutions Flashcards
(14 cards)
What is electrolysis?
Electrolysis is splitting a compound into its elements using electricity.
Why must ions be free to move in electrolysis?
So they can carry charge and be attracted to electrodes.
How are aqueous solutions made into electrolytes?
By dissolving ionic compounds in water to allow ions to move freely.
What additional ions are present in aqueous solutions?
Hydrogen (H⁺) and hydroxide (OH⁻) ions from the water.
What does the cathode attract?
Positive ions (metal ions and H⁺).
Which positive ion gets discharged at the cathode?
The least reactive one (compare metal vs. hydrogen using reactivity series).
When will hydrogen be discharged at the cathode?
If the metal is more reactive than hydrogen.
When will the metal ion be discharged at the cathode?
If the metal is less reactive than hydrogen (e.g. copper).
What does the anode attract?
Negative ions (e.g. OH⁻, Cl⁻, SO₄²⁻).
Which negative ion gets discharged at the anode?
Halide ions (Cl⁻, Br⁻, etc.) are discharged. If no halide, OH⁻ is discharged.
What happens if OH⁻ is discharged at the anode?
Forms water and oxygen gas: 4OH⁻ → 2H₂O + O₂ + 4e⁻.
What happens during electrolysis of copper sulfate?
Copper (Cu²⁺) is discharged at the cathode (forms solid copper). OH⁻ is discharged at the anode (forms oxygen).
What happens during electrolysis of sodium chloride?
H⁺ is discharged at cathode (forms hydrogen gas). Cl⁻ is discharged at anode (forms chlorine gas).
Why is the reactivity series important in electrolysis?
It helps decide whether the metal or hydrogen will be discharged at the cathode.
