Redox Reaction

[NguyenDDS]

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A redox reaction involves a change in oxidation number.

If we have this following reaction:

FeCl2 + NaOH --> Fe(OH)2 + 2NaCl

Why isn't this a redox reaction?

Isn't the Cl changing from a -2 to a -1?????????? Can someone please clarify this for me? THANKS!! 🙂

 

[herkulease]

Is this from destroyer its looks familar but anyhow.

Cl in FeCl2 is -1

its still -1 when it is with NaCl.

Iron is most commonly Fe2+ or Fe3+

in this case it is Fe2+.

There are no changes in oxidation number for anything.

 

[jkb53433]

A redox reaction involves a change in oxidation number.

If we have this following reaction:

FeCl2 + NaOH --> Fe(OH)2 + 2NaCl

Why isn't this a redox reaction?

Isn't the Cl changing from a -2 to a -1?????????? Can someone please clarify this for me? THANKS!! 🙂

redox reactions require oxidation and reduction. in this reaction you see reduction but no oxidation..therefore no redox reaction. know this concept

 

[invictusx]

A redox reaction involves a change in oxidation number.

If we have this following reaction:

FeCl2 + NaOH --> Fe(OH)2 + 2NaCl

Why isn't this a redox reaction?

Isn't the Cl changing from a -2 to a -1?????????? Can someone please clarify this for me? THANKS!! 🙂

Cl- isn't changing from a -2 to a -1. It's still -1. If it were ionized, it would be Fe+2 and Cl-.
Fe+2 + Cl- --> FeCl2 => see how you could just make the charge on the iron (+2) be chlorine's subscript? The -1 on chlorine would be iron's subscript, but you wouldn't write down Fe1Cl2. You just swap those two numbers.
Another one would be FeCl3 <---- Fe+3 + Cl-
Right? Another example would be: Ca+2 + OH- --> Ca(OH)2

So you can use that as a mnemonic device.

Overall, this isn't redox because every atom in the reaction retains its oxidation number.

 

[NguyenDDS]

Thanks everyone! I think I just got confused on how to identify oxidation numbers... I guess I need more practice. 🙂

Invictusx, the way you explained it realllllllllly helps me with this. Thanks so much! 🙂

 

[invictusx]

Thanks everyone! I think I just got confused on how to identify oxidation numbers... I guess I need more practice. 🙂

Invictusx, the way you explained it realllllllllly helps me with this. Thanks so much! 🙂

My pleasure! I'm glad it helped you out!! 😀

Also, halogens don't really change oxidation numbers--that's also something to know. I'm not specifically sure but my guess is that halogens are near to stable [not saying it is, just saying it's pretty stable] like the noble gases so by taking electrons off requires a HUGE amount of energy, not as much as plucking electrons off noble gases since the atom is fully filled with electrons (octet rule) and thus stable.

Recall the periodic table trends. As you go right and up, the atomic radius decreases. Because the atomic radius is smaller for halogens, electrons are more packed near the nucleus, thereby stabilizing it and thus requires a lot of energy to strip that electron off. You can also think of this as ionization energy. You probably won't take the electron off (therefore changing the oxidation number) because it would be wasteful energy!

BUT! This is merely a guess for why halogens maintain their oxidation number. Someone should counter this right now, hahaha

 

[loveoforganic]

redox reactions require oxidation and reduction. in this reaction you see reduction but no oxidation..therefore no redox reaction. know this concept

There can't be oxidation without reduction. There is neither here.

 

[MrFantastik]

Also, halogens don't really change oxidation numbers--that's also something to know. I'm not specifically sure but my guess is that halogens are near to stable [not saying it is, just saying it's pretty stable] like the noble gases so by taking electrons off requires a HUGE amount of energy, not as much as plucking electrons off noble gases since the atom is fully filled with electrons (octet rule) and thus stable.

Recall the periodic table trends. As you go right and up, the atomic radius decreases. Because the atomic radius is smaller for halogens, electrons are more packed near the nucleus, thereby stabilizing it and thus requires a lot of energy to strip that electron off. You can also think of this as ionization energy. You probably won't take the electron off (therefore changing the oxidation number) because it would be wasteful energy!

BUT! This is merely a guess for why halogens maintain their oxidation number. Someone should counter this right now, hahaha

I think you pretty much got it right except for one minor detail. In HOCl the H is +1, the O is -2, and the Cl is +1. Oxygen can change the oxidation # of all the halogens besides fluorine. But youre right, most of the time the halogens are -1. (so not a counter...just the exception that proves the rule 😉)

 

[invictusx]

I think you pretty much got it right except for one minor detail. In HOCl the H is +1, the O is -2, and the Cl is +1. Oxygen can change the oxidation # of all the halogens besides fluorine. But youre right, most of the time the halogens are -1. (so not a counter...just the exception that proves the rule 😉)

Oh, haahah yea. But didn't I mention that it more or less shouldn't change oxidation?! 😀 But, yeah, I forgot to mention that little detail. Nice! hahaa

 

[loveoforganic]

Reactions with diatomic halides are likely to be redox as well (obviously). Just another example