Haha. CHEMISTRY! xD Lets talk about.. OXIDATION & REDUCTION! 
Yup. I myself am not too sure on this chapter. But heck, I’ll try my best to explain.
Okay. Firstly, I find this useful to memorise.
Oxidation is..
- The GAIN of Oxygen
- The GAIN in Oxidation State
- The LOSS of Hydrogen
- The LOSS of Electrons
Reduction is..
- The GAIN of Hydrogen
- The GAIN of Electrons
- The LOSS of Oxygen
- The LOSS in Oxidation State
Okay, as you can see, their just the opposite of each other, so you can just memorise one, and reverse it to get the other. So for example, when Fe2O3 is put into the blast furnace, Fe is extracted. The exact equation for this is [Fe2O3 + CO --> 2Fe + 3CO2]. As you can see, Fe2O3 turns into Fe on the other side of the equation. Where did the Oxygen go to? It combined with the Carbon Monoxide at the start of the reaction, to form Carbon Dioxide. Thus, Fe2O3 loses Oxygen atoms, and hence, is REDUCED. However, CO turned into CO2. It gained 1 Oxygen atom. Therefore, it is OXIDISED.
The concept of Oxidising/Reducing agents. Fe2O3 is a OXIDISING AGENT, as it provides the Oxygen for CO to take in. So the OXIDISING AGENT provides the oxygen needed for the reaction. This is exactly the same as the REDUCING AGENT, except it takes in the Oxygen provided by the Oxidising Agent. So there you have it, the OXIDISING AGENT provides, and the REDUCING AGENT takes in.
REDOX Reaction. WHERE THE HECK DID THIS COME FROM? Like, its from Reduction-Oxidation reaction? Yeah, like, theres both Reduction and Oxidation in 1 reaction? I mean, it happens all the time. Like, if one reagent is oxidised, the other one is definatly reduced right? So.. like the above equation, [Fe2O3 + CO --> 2Fe + 3CO2], Haematite is REDUCED, and Carbon Monoxide is OXIDISED. Hence, there is both reduction and oxidation in the reaction, thus, it is called a Red(uction)Ox(idation) reaction. Hence, the name REDOX. See the link?
The gain/loss of HYDROGEN is exactly the same concept as the gain/loss of oxygen, so I won’t go through it. However, the gain/loss of Electrons is something quite confusing at times, so I’m gonna go through it as detailed as I can.
One of the most important REDOX reactions are the transfer of electrons, where one substance gives up electrons and another subtance takes in electrons. For example, in the forming of an ionic compound, [2Na + Cl2 --> 2Na(+)Cl(-)] Sodium as a metal exists on its own, hence it does not have an ionic charge. However, when it is reacted with Chlorine, it forms an ionic compound, NaCl, hence it gains its ionic charge. In this reaction, Na, from 0 charge, becomes a +1 charge. This is because the Sodium atom gave away its only valence electron, so as to form a full outer shell. Hence, the Sodium atom is Oxidised as it gives up electrons. You can also see that it gains in Oxidation state (ionic charge), hence, you can also deduce that it is oxidised from there, depending on what the question asks you. Chlorine, as a diatomic molecule, exists with covalent bonding. Hence, it also exists as a neutrally charged atom. By reacting it with Sodium, it forms an ion, just like Sodium. Hence, Chlorine takes in 1 electron, so as to complete its outer shell. Thus, you can see that it GAINS electrons, and hence be able to say that it is Reduced. And because it gains 1 electron, its ionic charge becomes -1. Hence, as it loses Oxidation State, you can also deduce from this that it is Reduced.
And of course, its all about Give & Take, now isn’t it? 
Hope it helps.
2006 GCE ‘O’ Level Combined Science(Chemistry)
allyourreadersarebelongtome. =x
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