Scroll to the bottom of the page for questions to test your understanding.
The concepts involved are
- electrolysis (molten and aqueous electrolytes, inert electrodes and active electrodes)
- chemical cell
Electrolysis with inert electrodes and molten electrolytes
The next two videos will cover
- the setup of an electrolytic cell (battery, electrolyte and inert electrodes)
- the positive and negative terminals of the battery
- the flow of electrons within the wires
- the positive and negative electrodes
- the movement of ions with the electrolyte
- oxidation at the anode, reduction at the cathode
- electrolysis of molten sodium chloride
- electrolysis of molten lead (II) chloride
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Electrolysis with inert electrodes and aqueous electrolytes
The next four videos will cover selective discharge during the electrolysis of
- dilute copper (II) sulfate
- dilute sodium chloride
- concentrated sodium chloride
- dilute sulfuric acid
Electrolysis with active electrodes
The next two videos will cover the application of electrolysis using active electrodes
- purification of impure copper
- electroplating using silver
Key points
The difference between active and inert electrodes occurs at the anodes.
Active anodes oxidise themselves into positive ions which goes into the electrolyte. Inert anodes oxidises the negative ions which are present in the electrolyte.
For electroplating with a desired metal,
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Chemical CellsThe difference between active and inert electrodes occurs at the anodes.
Active anodes oxidise themselves into positive ions which goes into the electrolyte. Inert anodes oxidises the negative ions which are present in the electrolyte.
For electroplating with a desired metal,
- cathode (negative terminal) will attract the metal ions
- anode (positive terminal) will release/replenish the metal ions
- electrolyte will contain the metal ion
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Electrons will flow from a more reactive to a less reactive metal.
Since the more reactive metal "supplies" the electrons, it is the negative terminal of the battery.
The terminal where oxidation takes place is known as the anode, the terminal where reduction takes place is known as the cathode.
Therefore, for chemical cells,
Negative terminal : oxidation, anode
Positive terminal: reduction, cathode
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Chemical Cells in an Electrolytic Cell
The diagram and table below shows the comparison of the redox reactions, the terminals of the batteries (chemical cells) are highlighted.
Key idea:
Region where oxidation takes place is always the "anode"
Region where reduction takes place is always the "cathode"
The diagram and table below shows the comparison of the redox reactions, the terminals of the batteries (chemical cells) are highlighted.
Key idea:
Region where oxidation takes place is always the "anode"
Region where reduction takes place is always the "cathode"
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Question 1
The electrolysis of a colourless aqueous solution using inert carbon electrode resulted in a dark brown colour solution at the anode and effervescence at the cathode. The substance present in the aqueous solution might be
A lead (II) iodide B sodium chloride
C copper (II) iodide D sodium iodide
Question 2
Which of the following electrolysis yields hydrogen at the cathode and oxygen at the anode
A aqueous copper (II) sulfate with copper anode
B aqueous copper (II) sulfate with platinum anode
C concentrated aqueous potassium chloride with platinum anode
D dilute sulfuric acid with platinum anode
Sir can you tell me about how to use electrode potential of A2 level.For example there are three potential value for cu which one should be used.Please suggest me sir
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