OIL RIG
These two words you are undoubtable familiar with since GCSE chemistry - or at least I would hope so! OIL RIG refers to oxidation and reduction, you may ask: what are these two terms? Well the definitions are simple:
Oxidation refers to the loss of electrons or the gaining of oxygen.
Reduction is the polar opposite as it refers to the gain of electrons and the loss of oxygen.
Oxidation and reduction are like two of your friends who really like each other and they never stop being together (weird analogy I know) as they always go hand in hand, somewhat of a package deal: you buy one, you get one free! When there is a reaction where reduction takes place, oxidation won't be far behind and vice versa, this is because when reduction occurs oxidation must take place also. It like that cringe quote: 'every action has an equal and opposite reaction.' which makes sense because they do the opposite of each other.
When reduction and oxidation occurs in a reaction they are known as redox reactions because well reduction (red) and oxidation (ox). This type of reaction ties in heavily with oxidation numbers as reduction decreases oxidation number and oxidation does the opposite by increasing said number (back to the cringe quote).
You can also tie this to ionisation energies and electron affinities to a degree as you use half equations displaying the loss or gain of electrons. So half equations can be written as simply as this:
Na ---------> Na+ + e- This is a half equation for oxidation as it has lost an electron.
Cl2 + 2e- ---------> 2Cl- This is a half equation for reduction as it has gained an electron.
You can use oxidation numbers with equations to figure out if an atom has been oxidised or reduced and remember both will occur if one is present.
2Al + 6HCl ------------> 2AlCl3 + 3H2
By looking at oxidation numbers you can see the following things:
H has gone from a 1+ oxidation state to a 0 oxidation state and thus this atom has been reduced as it has gained an electron. This occurs because when H2 is acting as an element the oxidation number will always be 0.
Al has started with an oxidation number of 0 because it has started as an element and is now in a 3+ state because of 3 chlorine atoms with a negative charge each are bonded to it and the overall molecular charge is 0 and thus the charges must be balanced.
Cl started in a -1 state and remains as -1 and thus has neither been reduced nor oxidised.
The reduced species is hydrogen and the oxidised species is aluminium. Chlorine was neither reduced nor oxidised and is dubbed a spectator ion as it does not take part in the redox reaction. Alternatively there are reactions where an atom can be both reduced and oxidised and these are known as disproportionation reactions. An example of this can be shown in the figure below.
Did you find this helpful? Feel free to drop a comment and let me know what you liked and if I have missed something!
These two words you are undoubtable familiar with since GCSE chemistry - or at least I would hope so! OIL RIG refers to oxidation and reduction, you may ask: what are these two terms? Well the definitions are simple:
Oxidation refers to the loss of electrons or the gaining of oxygen.
Reduction is the polar opposite as it refers to the gain of electrons and the loss of oxygen.
Oxidation and reduction are like two of your friends who really like each other and they never stop being together (weird analogy I know) as they always go hand in hand, somewhat of a package deal: you buy one, you get one free! When there is a reaction where reduction takes place, oxidation won't be far behind and vice versa, this is because when reduction occurs oxidation must take place also. It like that cringe quote: 'every action has an equal and opposite reaction.' which makes sense because they do the opposite of each other.
When reduction and oxidation occurs in a reaction they are known as redox reactions because well reduction (red) and oxidation (ox). This type of reaction ties in heavily with oxidation numbers as reduction decreases oxidation number and oxidation does the opposite by increasing said number (back to the cringe quote).
You can also tie this to ionisation energies and electron affinities to a degree as you use half equations displaying the loss or gain of electrons. So half equations can be written as simply as this:
Na ---------> Na+ + e- This is a half equation for oxidation as it has lost an electron.
Cl2 + 2e- ---------> 2Cl- This is a half equation for reduction as it has gained an electron.
You can use oxidation numbers with equations to figure out if an atom has been oxidised or reduced and remember both will occur if one is present.
2Al + 6HCl ------------> 2AlCl3 + 3H2
By looking at oxidation numbers you can see the following things:
H has gone from a 1+ oxidation state to a 0 oxidation state and thus this atom has been reduced as it has gained an electron. This occurs because when H2 is acting as an element the oxidation number will always be 0.
Al has started with an oxidation number of 0 because it has started as an element and is now in a 3+ state because of 3 chlorine atoms with a negative charge each are bonded to it and the overall molecular charge is 0 and thus the charges must be balanced.
Cl started in a -1 state and remains as -1 and thus has neither been reduced nor oxidised.
The reduced species is hydrogen and the oxidised species is aluminium. Chlorine was neither reduced nor oxidised and is dubbed a spectator ion as it does not take part in the redox reaction. Alternatively there are reactions where an atom can be both reduced and oxidised and these are known as disproportionation reactions. An example of this can be shown in the figure below.
Did you find this helpful? Feel free to drop a comment and let me know what you liked and if I have missed something!
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