Sciencemadness Discussion Board

What is an oxidizing agent?

Turner - 12-3-2014 at 19:04

I have always understood something that is an oxidizer is something that can readily decompose and give off oxygen, or Carbon is oxidized in this case: C + O2 =--> CO2

Lately I've been studying this more, oxidation and reduction and understand now that something is oxidized if it is getting electrons taken away, reduced if it is given electrons, the oxidizer get's reduced and the reducer get's oxidized, this has been difficult to wrap my mind around.

Can someone show/explain to me how both of these separate truths can be combined into one idea?

Also I am struggling with this:

Cu + HNO3 --> CuNO3 + H2 + NO2 blah blah

copper must be exposed to an oxidizing agent (nitric acid in order to split into it's ions) why is a nitrate ion an oxidizer? Why not a Cl- ion as in the case of HCL? Because I know that no reaction occurs with HCL and copper.

DraconicAcid - 12-3-2014 at 19:18

An oxidizer is something that will take away electrons. Period. Many oxidizers *contain* oxygen, and can give it off when heated, but it's not a requirement- fluorine, chlorine, and chlorine trifluoride are very good oxidizers without containing any oxygen.

Nitric acid acts as an oxidizer because the nitrogen takes an electron to go from the +5 oxidation state in HNO3 to +4 in NO2. Chlorine in hydrochloric acid is -1 already- it cannot take any more electrons, and cannot oxidize copper.

Turner - 12-3-2014 at 19:29

Why isn't N2 an oxidizer like O2 is? Is Cl2 an oxidizer? Can it oxidize something in combustion? Do you have an example?

Thanks

[Edited on 13-3-2014 by Turner]

DraconicAcid - 12-3-2014 at 20:01

Chlorine is an oxidizer. Some examples:

H2S + 2 Cl2 -> 2 HCl + SCl2

2 Fe + 3 Cl2 -> 2 FeCl3

Nitrogen is a lousy oxidizer because it's not so electronegative. It can act as one, but won't take electrons from many other elements.

6 Li + N2 -> 2 Li3N

woelen - 12-3-2014 at 23:45

The word 'oxidizer' is used in two different ways.

The most used meaning is: A compound which easily oxidizes other materials. Examples are oxygen, potassium chlorate, nitric acid, fluorine, chlorine, potassium permanganate.

The more formal meaning is: A compound, which takes electrons from another compound in its reactions. In this sense, many compounds which normally are not considered oxidizer can act as oxidizer. Even water can act as oxidizer, e.g. 2 H2O + 2 Na --> 2NaOH + H2. When a sufficiently strong reductor is present, many compounds which are normally not considered oxidizer can work as oxidizer.

Some compounds can act both as reductor (in many contexts it is called 'fuel') or as oxidizer, e.g.:

Zn + S --> ZnS (sulphur as oxidizer)
S + O2 --> SO2 (sulphur as reductor, sulphur being the 'fuel' in the fire)

HeYBrO - 13-3-2014 at 01:55

Quote: Originally posted by Turner  
Why isn't N2 an oxidizer like O2 is?

[Edited on 13-3-2014 by Turner]


Because nitrogen gas has a very strong triple bond-essentially stopping reactions at SLC. A lot of energy is required to break the bond to form other compounds.

vmelkon - 13-3-2014 at 03:57

Quote: Originally posted by HeYBrO  
Quote: Originally posted by Turner  
Why isn't N2 an oxidizer like O2 is?

[Edited on 13-3-2014 by Turner]


Because nitrogen gas has a very strong triple bond-essentially stopping reactions at SLC. A lot of energy is required to break the bond to form other compounds.


That's what I read but I think there is more to it than that. The target compound is probably not stable, so for example, if you heat iron in nitrogen gas, it doesn't form iron(II) nitride.
Compare that to heating iron with other non-metals and metalloids. If you use iron and carbon, you will end up with iron carbide (I guess FeC).

So I think that most nitrides are unstable.

Zyklon-A - 13-3-2014 at 07:14

Another reason azides ate unstable, is because making compound with nitrogen is almost always endothermic. And when many nitrogen atoms are in close proximity to one another, they tend to try to bond to form their stable N-N triple bond.