Post by: lazykid on October 11, 2010, 08:58:39 pm
-which is the oxidant/reductant
-half equations etc..
-galvanic cells: -which is the anode/cathode
-which element is more reactive
thanks heaps :)
Post by: Edmund on October 11, 2010, 09:06:39 pm
Example:
Fe(s) + CuSO4(aq) ---> FeSO4(aq) + Cu(s)
Cu2+ gets reduced and is therefore an oxidant. Cu is the conjugate reductant.
Fe gets oxidised and is therefore a reductant. FeSO4 is the conjugate oxidant.
OxidAtion takes place at the Anode. This is were electrons are lost.
ReduCtion takes place at the Cathode. This is where electrons are gained.
Post by: luken93 on October 11, 2010, 09:06:51 pm
RED CAT = REDuction occurs at the CAThode
Half Equations:
Refer to your Electrochemical Series (in the Chem Databook
Start at the top of the list (Which is F2)
Move down the page, until you see your first substance eg. Cu
The first substance half eq will be:
eg. Cu2+ + 2e- -->Cu
Hence,
The secod substance half eq will be:
eg. Zn --> Zn2+ + 2e-
The same goes for which element is more reactive, the higher it is on the electrochemical series, the more reactive it is.
Post by: vea on October 11, 2010, 09:07:12 pm
Reductant- The more reactive metal
Half Equations
When balancing:
1. Balance atoms that are not O or H
2. Balance O by adding water (H2O)
3. Balance H by adding H+
4. Balance electrons
5. Then multiply the half equations by a constant so that there are the same amount of electrons on each side.
Anode- Oxidation occurs here (the ones starting with vowels) so it is the reductant.
Cathode- Reduction occurs here (the ones starting with consonants) so it is the oxidant.
IMO the best way is to learn by practice.
Post by: cypriottiger on October 11, 2010, 09:11:07 pm
i remember reduction my looking at me ECS in the data book and thinking which equation reduces in content. this occurs left to right, so reduction occurs when the reaction progresses left to right, so at the cathode (top-left). as thats reduction the opposite of everything must occur at the bottom-right, oxidation. oxidant is that chemical that CAUSES the OTHER reaction to occur by oxidation, and vice-versa for reductant.
in terms of reactivity ill let someone else answer because i dont feel as though i could give you the best response.
Post by: Mao on October 11, 2010, 11:02:07 pm
K ey element
O xygen by adding water
H ydrogen by adding H+
E lectrons by adding electrons
S tates
B ase to balance H+ in the case of alkaline environments (such as in fuel cells) - optional
Post by: SixWinged on October 12, 2010, 05:48:02 pm
Post by: ttn on October 12, 2010, 06:44:53 pm
An OIL RIG Cat
Anode for Oxidation is losing e-
Cathode for Reduction is gaining e-
Post by: happyhappyland on October 12, 2010, 06:58:06 pm
Post by: andy456 on October 12, 2010, 08:00:03 pm
for galvanic cells....
Anode : oxidation involves loss
Cathode: reduction involves gain
Cat's are warm and fuzzy and make you feel happy hence the positive.
Anode then becomes -
Electrolysis
+ An OIL RIG Cat -
Everything applies but when you add electricity to cat's what happens; (-) negative
Post by: rashmi_34 on October 16, 2010, 04:11:46 pm
KOHES (B) is the way to go
Post by: kyzoo on October 16, 2010, 05:54:38 pm
I just use my own "Law of Equivalent Trade" thingy
Oxidation = Gain oxygen, so you lose electron. Thus electrons produced by reaction.
Reduction = Lose oxygen, so you gain electron. Thus electrons consumed by reaction.
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As for oxidant/reductant. I just use oxidant = reduced substance, reductant = oxidised substance.
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Anodes and Cathodes
A comes before C, so A --> C
Electrons go from A to C.
Electrons produced at Anode and transmitted to Cathode