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Electrochemistry chem 5! help

(c) The cell represented below was set up under standard conditions.
Pt|Fe2+(aq), Fe3+(aq)||Tl3+(aq),Tl+(aq)|Pt Cell e.m.f. = + 0.48 V

(i) Deduce the standard electrode potential for the following half-reaction.
Tl3+(aq) + 2e– Tl+(aq)
...........................................................................................................................
...........................................................................................................................
(ii) Write an equation for the spontaneous cell reaction.
...........................................................................................................................



Hi everyone i did the Q did it well - apart from spontaneous reaction i got 2fe3+ + Tl3+ ====) 2Fe2+ + Tl+

This was by using the anti-clockwise rule = however - the real answer for the Q was

Tl3+ + 2 Fe2+ ===) 2Fe3+ + T1+

Need an explanation why thanks!
Original post by ahsan_ijaz
(c) The cell represented below was set up under standard conditions.
Pt|Fe2+(aq), Fe3+(aq)||Tl3+(aq),Tl+(aq)|Pt Cell e.m.f. = + 0.48 V

(i) Deduce the standard electrode potential for the following half-reaction.
Tl3+(aq) + 2e– Tl+(aq)
...........................................................................................................................
...........................................................................................................................
(ii) Write an equation for the spontaneous cell reaction.
...........................................................................................................................



Hi everyone i did the Q did it well - apart from spontaneous reaction i got 2fe3+ + Tl3+ ====) 2Fe2+ + Tl+

This was by using the anti-clockwise rule = however - the real answer for the Q was

Tl3+ + 2 Fe2+ ===) 2Fe3+ + T1+

Need an explanation why thanks!


Forget the anticlockwise "rule". Examiners can throw in a spanner by writing the list in a different order.

Spontaneous reaction requires that E(reduced half-equation) - E(oxidised half-equation) = positive value

Mnemonic E = E(red-ox)
Reply 2
Yeah I realised the cycle works - you just have to right them both as reduction equations


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Original post by charco
Forget the anticlockwise "rule". Examiners can throw in a spanner by writing the list in a different order.

Spontaneous reaction requires that E(reduced half-equation) - E(oxidised half-equation) = positive value

Mnemonic E = E(red-ox)


i think there some information is missing there
(edited 7 years ago)
Original post by tinashe dongo
i think there some information is missing there


No, there isn't ...
Reply 5
Original post by tinashe dongo
i think there some information is missing there


The equation you get using anti clockwise rule is correct - but you need to remember to right the more negative e cell on top and less negative on bottom and both as reduction reactions so species at non pointy end of arrow will react to give the species at pointy end



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