So yeah.
In electrolysis, a current is carried by both positive and negative charges. Here's what it looks like...
The negative electrode -
- is known as the cathode
- always attracts the positive molecules (which are always metals or hydrogen)
- allows the positive metals to gain a couple of electrons so they can go back to being a normal atom.
The positive electrode -
- is known as the anode
- always attracts negative molecules
- allows the negative part of a substance to loose a few electrons so it can go back to being a normal atom too.
Quite simply, opposites attract.
We use electrolysis for -
- electroplating
-on submarines so they don't rust
- and one space craft so they're light but aren't damaged on take off.
Electrolysis of aluminium is an important one I have to learn...
Bauxite is mined out of the ground and purified to make aluminium oxide. The aluminium oxide is then mixed with cryolite to bring down it's melting point, because the aluminium has to be molten to conduct the electricity. Then, the aluminium oxide and cryolite is chucked in a tank that looks like this...
The anode has to be replaced every few months, because when the oxygen is separated from the aluminium, it begins to react with the carbon in the anode and produce CO2.
At the cathode, this happens...
Al^3 + 3e > Al
In other words, the ion aluminium is given 3 extra electrons to make it normal.
At the anode, this happens...
2O^2- > O2 - 4e
Aka, the oxygen ion gets rid of four electrons.
Yay, electrolysis finished. Happy Gaby.
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