Urgent A/S Chem: Redox & Oxidation States

Hi I am unsure of this question, as my teacher didn't have time to complete the course before study:

2H20 + SO2 + 2[CuCl4]2- => 4H+ SO42- + 4Cl- + 2[CuCl2]-

Identify the element being reduced in this reaction and write a half equation for the reduction of the species containing this element.

Reply 1

kriztinae

14

supreme

Hi I am unsure of this question, as my teacher didn't have time to complete the course before study:

2H20 + SO2 + 2[CuCl4]2- => 4H+ SO42- + 4Cl- + 2[CuCl2]-

Identify the element being reduced in this reaction and write a half equation for the reduction of the species containing this element.

hmm well i sulpher is being oxidised from +4 to +6
and copper is being reduces from +2 to +1
think thats right. hope it helps

Reply 2

supreme

OP

4

kriztinae

hmm well i sulpher is being oxidised from +4 to +6
and copper is being reduces from +2 to +1
think thats right. hope it helps

Thank you very much :smile:

Reply 3

z!D4N

who has a clear definition of 'oxidation number'?

Reply 4

kriztinae

14

supreme

Thank you very much :smile:

hehe no problem! :rolleyes:

Reply 5

z!D4N

who has a clear definition of 'oxidation number'?

anyone?

Reply 6

GH

13

z!D4N

anyone?

The difference between the number of electrons associated with an element in a compound and the element itself

Reply 7

z!D4N

2776

The difference between the number of electrons associated with an element in a compound and the element itself

thank you!

Reply 8

Sahir

2

z!D4N

who has a clear definition of 'oxidation number'?

For EdExcel we were told "the formal charge assigned to an atom or ion to decide its relative state of oxidation or reduction, assuming all compounds and complex ions are wholly ionic"

For the half equations, by the way.. i got..

SO2 (aq) + 2H2O (l) <---> SO4^2- (aq) + 2e^- + 4H+ (aq)
so sulfur is oxidised from a an ox state of +4 to +6

and

[CuCl4]^2- + e^- <---> [CuCl2]^- + 2Cl^-
so copper is reduced from a state of +2 to +1

I think that's right, yea.. tis. Seeing as they're redox equations, i'm right to use reversible sign thingys, no?!

EDIT: no wait the reduction half equation was wrong.. fixed it now.

Reply 9

supreme

OP

4

Thanks Sahir.

In my revision book it gives the definition of oxidation states as:

•

describes atoms, molecules or ions

•

shows how many electrons have been used in bonding

•

can be appliied to all substances, no matter what the type of bonding

•

is often give the abbreviation Ox (or ON)

Reply 10

Sahir

2

supreme

Thanks Sahir.

In my revision book it gives the definition of oxidation states as:

•

describes atoms, molecules or ions

•

shows how many electrons have been used in bonding

•

can be appliied to all substances, no matter what the type of bonding

•

is often give the abbreviation Ox (or ON)

That'll be useless Letts revision guides then?! Okay it tells you what's going on.. but you can hardly write that in an exam, it's very vague!

Reply 11

supreme

OP

4

Lol but that was Paddy and it is a great book :smile:

Reply 12

Happyelf

The oxidation number is defined as the sum of negative and positive charges in an atom, which indirectly indicates the number of electrons it has accepted or donated.
or u can have this one if u prefer....
The oxidation number is the charge an atom would carry if the molecule or ion were completely ionic
Lu x
p.s - could someone please look at my other chemistry post please...really need help with that question.

Urgent A/S Chem: Redox & Oxidation States

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