A redox reaction question - please help!?

Question

If copper turnings are boiled in concentrated sulphuric acid then transferred to water the colour of the solution goes blue. I'm trying to write the redox equation but i'm stuck as to what gets reduced. Am i right in saying the Cu is oxidised to Cu2+ ? If so is it the H that is reduced? Thanks in advance...

Answer 1

hmm. copper is a tricky metal. firstly conc. sulphuric acid and nitric acid are the only acid that would react as they are also strong oxidising agents. What happens when u dip the turning is that the copper is oxidised into copper(II)oxide and the sulphate ion is reduces to sulphite SO3 2-. I think so but not too sure if i'm right.

Answer 2

Overall equation:
Cu + H2SO4 --> CuSO4 + H2
copper + sulphuric acid ---> copper sulphate (blue) + hydrogen


Redox eqtns:


Cu --> Cu 2+ + 2e- (oxidisation of copper)

SO4 2- + 8H+ + 6e- ---> S + 4H20 (reduction of sulphur)


explanation:
oxidation state of oxygen= -2
SO4 2- : O(-2 x 4) = -8 overall oxygen+sulphur= -2 so -8+ 6=-2 ie. oxidation state of sulphur is 6
As the oxidation state of an element is always 0, in the second part of the equation oxidation state of S=0, so sulphur goes from oxidation state +6 to 0, hence it is reduced (OIL RIG; oxidation is loss of electrons, reduction is gain).


Hydrogen is not reduced, it remains in the same oxidation state (+1)

To complete the question, you may need to add the equations.
Multiply equation 1 (the oxidation of copper) by 3 so that you have 6 electrons (this balances eqtn 2). Then add them like so:

3Cu ---> 3Cu2+ + 6e-

+

SO4 2- + 8H+ + 6e- ---> S + 4H20

= 3Cu + SO4 2- + 8H+ ----> 3Cu2+ + S + 4H20

The electrons cancel out.


Hope this helps! :) Gave my brain a work-out!

Answer 3

hi, ive bin asked to make copper sulphate solution (blue solution) befor. n copper does not react with sulphuric acid so normally, we'd have 2use coper(ll)oxide. which produces copper(ll) sulphate solution along with other products.
but if it DID react in the above proceedure as you hv descibed
then yeah the copper has been oxidised to +2 from 0. and H has been reduced from +2 to 0. the S in this reaction is the spectator ion since it remains at +6.
Hope that helped.
email if yu still feel you need help. ive been there wer you are. lol. i know how confusing Chem can be.
x

Answer 4

Hydrogen is reduced from +1 to 0. Remember that oxidation state for homonuclear diatomics (H2, O2) etc is 0. Cu to Cu2+ is correct.

Answer 5

I flink it is the flux capacitator that ends up reduced, but you better watch what you are doing when doing these experiments in case you make the world implode. x x x

Answer 6

Cu(s)+4H+(aq)+SO42-(aq)-heat->
Cu2+(aq)+SO2(g)+2H2O(l)