- Battery
- Positive electrode (anode) — connected to positive terminal of battery
- Negative electrode (cathode) — connected to negative terminal of battery
- Connecting wires (connect battery to anode and cathode)
- Electrolyte
- Bulb/ammeter (these components are optional)
Label parts of electrolytic shell in the figure below insert image here later
What are Electrodes?
- Substances which are good conductors of electricity in solid state (electrical conductors)
- Able to conduct electricity → due to presence of delocalised electrons which can move freely from negative terminal to positive terminal of the conductor Properties of Metals
- Thus electrodes are usually made of → metal plates or graphite rods
- Material of electrode determines reactivity.
2 types of electrodes:
| Type of electrode | Inert electrode | Reactive electrode |
|---|---|---|
| Material of electrode | - Graphite (allotrope of carbon) - Platinum Allotrope: Properties of Covalent Compounds | - Any metal → which is more reactive than platinum (refer to Reactivity Series Main Note) |
| Difference between these 2 types of electrodes | - If anode is an inert electrode → it remains chemically unchanged (does not undergo oxidation reactions) → when electric current flows through it. - Anode will NOT interfere with → type of ions that are discharged. - Anode does not react with electrolyte or products of the electrolysis | - If anode is reactive electrode → it will undergo chemical reaction (oxidation reaction) → when electric current flows through it Hence → anode WILL interfere with type of ions that are discharged. |
| Similarity between these 2 types of electrodes | Cathode remains chemically unchanged (does not undergo reduction reaction) → when electric current flows through it. Hence → cathode → will not interfere with discharge of ions Cathode → does not react → with electrolyte / products of the elcetrolysis | Cathode remains chemically unchanged (does not undergo reduction reaction) → when electric current flows through it. Hence → cathode → will not interfere with discharge of ions Cathode → does not react → with electrolyte / products of the elcetrolysis |
Note
What it means when it says that it does not undergo oxidation reactions for inert electrodes is that the ELECTRODE ITSELF remains unchanged. This has no impact on the oxidation that occurs at the anode.
Important
Electrons always flow from the cathode to the anode From negative terminal of battery to positive…
Note
anode (positively charged electrode) is connected to positive end of battery and cathode (negatively charged electrode) is connected to negative end of battery
Definition
Inert electrodes are electrodes that do not take part in electrolysis
Not all allotropes of carbon can make electrodes, only graphite
Note
properties for a good inert electrode:
- good COE
- not easily corroded by gasses
- unreactive metal → will not react with ions, and remains chemically unchanged
inert electrode will not undergo oxidation or reduction as it is inert and unreactive → thus it will not interfere with the discharge of ions it does not react with the electrolyte or the products formed