I'm having trouble with Redox reactions

[Veloce]

Can someone explain how to determine the reducing agent and oxidizing agent and what is oxidized or reduced?

I understand that the reducing agent gets oxidized meaning it loses electrons, and that the oxidizing gets reduced meaning it gains electrons, but i'm getting every question wrong.

Is the reducing/oxidizing agent always on the reactant side or can it be on both sides?

None of my references explain it in a way I can understand.

Thanks

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[scottkennedy29]

The Oxidizing agent removes electrons from another substance by acquiring them itself. This means that the oxidizing agent itself is reduced (the substance gaining the electrons).

The Reducing agent is the exact opposite. It will be the substance that is loosing electrons.

And people can correct me if i'm wrong but these agents will always be in the reactants side of the equation.

The Brown, lemay and bursten chem book explains this really well. (P. 849)

 

[Nateftw]

So you know that if something looses electrons, it's being oxidized, and if it gains electrons it is being reduced.

The reducing AGENT, is the molecule that causes another molecule to be reduced. In this process, the reducing agent itself gets oxidized.

Conversely, an oxidizing AGENT, is the molecule that causes another molecule to be oxidized. In this process, the oxidizing agent itself is reduced.

On each side of your equation, there should be one molecule that gets reduced, and one molecule that gets oxidized (but not always). Anyways, start off by assigning formal charges to each atom in each molecule. Remember that the sum of the formal charges in any molecule should be zero as long as the molecule has no charge on it. So for example, H2O, 0= -2, H= +1. 1+1-2=0. Also, molecules in their standard states have no formal charges, ie N2, O2, etc.

Example:

4Fe + 3O2--> 2Fe2O3

Assigning formal charges:
Reactants: Fe shows no charge, so it has a formal charge of 0. Same with O2

Products: 0 has a negative charge of -2. So -2x3= -6. The Fe must balance the -6 to insure that the sum is zero. So it must have a charge of +3 because there are two Fe atoms. +3*2=+6. +6-6=0.

Conclusion: Fe went from having no formal charge, to a +3 formal charge. So it is being oxidized. This means that it is the reducing agent (causes something else to be reduced). So what gets reduced? O2 does, goes from a formal charge of 0 to -2.

Sorry if I was confusing, I hope that helped.

 

[flyingforever]

Go through the rules when assigning oxidation numbers.
Oxidation-increase in number (reducing agent)
Reduction- decrease in number (oxidizing agent)

 

[Veloce]

I watched chad's video a few more times, and it seems like both the reducing agent and the oxidizing agent, and also the molecule that is reduced and oxidized is on the reactant side.

Is this correct?

Chad states that the molecule that is oxidized and the molecule that is oxidized is always on the reactant side, is it the same for the reducing and oxidizing agent?

 

[siffe]

Yes, you should always look at the reactant side.

No matter if you're talking about oxidation/reduction or oxidizing/reducing agent, you should always look at the reactant side.

 

[RUpremed]

first determine what is being oxidized and what is being reduced...

for ex. Fe2+--->Fe+ is being reduced because it is going from 2+ to +
Ag+---->Ag 2+ is being oxidized because it is going from + to 2+

and with regards to oxidizing and reducing agents...whatever is being oxidized is the reducing agent, and whatever is being reduced is the oxidizing agent. but remember, when you're dealing with compounds, the whole compound is the oxidizing/reducing agent, not just the element that is being oxidized/reduced. hope this helps.