Chemistry redox

Lucky10

Can someone go through a couple of these, and show me how to go about one?

(edited 7 years ago)

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Reply 1

CheeseIsVeg

Original post by Lucky10

Can someone go through a couple of these, and show me how to go about one?

Of course!
Let us start with SO2
Tell me what you know about the oxidation numbers of them already :smile:

Reply 2

Lucky10

Original post by CheeseIsVeg

Of course!
Let us start with SO2
Tell me what you know about the oxidation numbers of them already :smile:

S has a +2 charge and that oxygen has a -2 charge??

Reply 3

CheeseIsVeg

Original post by Lucky10

S has a +2 charge and that oxygen has a -2 charge??

Ok but remember with redox. If there are 2 non-metals, the most electronegative has te negative charge. Here this is oxygen, so it's oxidation number is -2.
This is a compound so that means the overall charge has to be 0.

So using this information. Sulphur must have a positive charge to counterbalance the 2 x (-2) (O2 = 2 times the -2 charge said above)
So Sulphur must be ...?

Reply 4

Lucky10

Original post by CheeseIsVeg

+2??

Reply 5

CheeseIsVeg

Original post by Lucky10

+2??

No
So as oxygen has an oxidation number of -2
THere are 2 of them (-4)
ANd 1 sulphur
As the compound is neutral, it will have to balance out the -4 from the oxygen. so sulphur is +4

Try another?

Reply 6

Lucky10

Original post by CheeseIsVeg

No
So as oxygen has an oxidation number of -2
THere are 2 of them (-4)
ANd 1 sulphur
As the compound is neutral, it will have to balance out the -4 from the oxygen. so sulphur is +4
Oh right thats helped and yeah it that's okay with you
Try another?

oh right, thats helped and yeah if thats fine by you

Reply 7

CheeseIsVeg

Original post by Lucky10

oh right, thats helped and yeah if thats fine by you

Yay

Do you mind posting one? on my phone and can't read the picture, sorry!

Reply 8

Lucky10

Original post by CheeseIsVeg

Yay

Do you mind posting one? on my phone and can't read the picture, sorry!

NaH

Reply 9

CheeseIsVeg

Original post by Lucky10

NaH

NaOH or NaH?

Reply 10

Lucky10

Original post by CheeseIsVeg

NaOH or NaH?

NaH please

Reply 11

CheeseIsVeg

Original post by Lucky10

NaH please

Ok. So we know sodium is a group one metal. What do you know about the group one metals? :smile:

Reply 12

OfficialChemist

Grp 1 is 1+, Grp 2 is 2+, Grp 3 is 3+, Grp 6 is 2-, Grp 7 is 1-, And u gotta know maybe ur standard ions such as (So4)2-, (PO4)3-, (NO3)-. (CO3)2-

Reply 13

Lucky10

Original post by CheeseIsVeg

Ok. So we know sodium is a group one metal. What do you know about the group one metals? :smile:

That it has 1 electron in its outer most shell

Reply 14

Lucky10

Original post by OfficialChemist

Grp 1 is 1+, Grp 2 is 2+, Grp 3 is 3+, Grp 6 is 2-, Grp 7 is 1-, And u gotta know maybe ur standard ions such as (So4)2-, (PO4)3-, (NO3)-. (CO3)2-

yeahh

Reply 15

Lucky10

Original post by Lucky10

yeahh

Would it be -1 as sodium has a charge of +1

Reply 16

CheeseIsVeg

Original post by Lucky10

That it has 1 electron in its outer most shell

So it would form an ion of +1, hence its oxidation state :wink:

Original post by Lucky10

Would it be -1 as sodium has a charge of +1

H would be -1, yes
Remember the overall charge of this is 0 so you can see H must be -1 is Na is +1 :smile:

Reply 17

Lucky10

Original post by CheeseIsVeg

So it would form an ion of +1, hence its oxidation state :wink:

H would be -1, yes
Remember the overall charge of this is 0 so you can see H must be -1 is Na is +1 :smile:

Can we do one where its a minus

MnO42-

Original post by Lucky10

MnO42-

Yep so, sorry was eating food!
So we have an ion here.
So whatever happens, we need the sum of the oxidation states to have a charge of -2

We've spoken about Oxygen always being -2
So here we have 4 oxygens, each with -2
-2 times 4 = -8

Now hold on

We need an overall charge of -2
The only other species we have here is Mn
so its oxidation number must be ?