ELECTROCHEMISTRY helP :(( (1 Viewer)

[OMGitsme]

hi
im really confused with electrochemistry...
okay i know that the cathode is negative and anode +ve with electrochemical cells(opposite to galvanic)
but say u had Ca 2+ and Zn 2+ what will occur at the anode and what will occur at the cathode... which one will be reversed and is it the same as galvanic cells?

and also... if ur solution has weak oxidants i.e weaker than water for insance Na+ and K+ does this mean they will both be reduced or oxidised?

ThaNks,,,,

 

[serge]

electrochemical cells (opposite to galvanic)

you are wrong you are thinking of ELECTROLYTIC
electrochemical just means electrical and chemical energy
is being converted the term doesnt specify whether its
a battery or electrolysis reaction

but say u had Ca 2+ and Zn 2+ what will occur at the anode and what will occur at the cathode...

what are your electrodes?
you've just mentioned there are cations in a solution

 

[rama_v]

Na+ and K+ are never ever reduced in solutions, only when they are in molten form. E.g. molten NaCl...I am presuming that you are using inert graphite/platinum electrodes. Water is reduced instead. So everything above water in that standard potentials data sheet will not be reduced.

 

[OMGitsme]

ooops,,, i meant electrolytic cells.. thanks anyway

 

[Haku]

hi
im really confused with electrochemistry...
okay i know that the cathode is negative and anode +ve with electrochemical cells(opposite to galvanic)
but say u had Ca 2+ and Zn 2+ what will occur at the anode and what will occur at the cathode... which one will be reversed and is it the same as galvanic cells?

and also... if ur solution has weak oxidants i.e weaker than water for insance Na+ and K+ does this mean they will both be reduced or oxidised?

ThaNks,,,,

for the first one cathode would be Zinc and anode is Ca. you have to reverse the half equation for the anode and the emf. water is always reduced at the cathode. depending on the solution, the one with the most positive oxidation potential in the electrolyte will be oxidised.

for the second one i am not sure what u mean by weaker oxidant. but Na+ and K+ has too high reduction potential and is never reduced at the cathode. water is reduced instead. while at the anode i am not too sure.

 

[Haku]

Na+ and K+ are never ever reduced in solutions, only when they are in molten form. E.g. molten NaCl...I am presuming that you are using inert graphite/platinum electrodes. Water is reduced instead. So everything above water in that standard potentials data sheet will not be reduced.

can Na+ and K+ get oxidised?

i think it cant

 

[rama_v]

can Na+ and K+ get oxidised?

i think it cant

Na can, but Na+ can't be oxidised, its already had its electron taken away lol

 

[Haku]

well didn't think of that. i was more thinking that its reduction potential is too high.