Electrolysis question (1 Viewer)

[NichNich]

Could anyone help me out on this problem please? This is question 29 in Shipwrecks and salvage in the 2002 paper, but electrolysis appears in the production of materials topic, so I posted this here.

Calculate the voltage required to operate the cell shown as an electrolytic cell, showing relevant half equations in your working.

The diagram is just an iron electrode on the left and a copper electrode on the right, with all the usual things in a electrolytic cell (salt bridge, elctrolyte etc)

**

In a galvanic cell, the iron would be the anode, and the copper elctrode would be the cathode, correct? Shouldn't an electrolytic cell be exactly the reverse? Ie. Iron the cathode, and copper the anode?

Yet the answers say that the iron remains the anode.... what the hell!?!?!

Any help would be much much much appreciated! Many thanks in advance!

 

[Gesus]

ahem, electrolytic != to electrolysis
took my a couple of seconds, but the diagram shows no power source is a extra clue

 

[LSP]

Could anyone help me out on this problem please? This is question 29 in Shipwrecks and salvage in the 2002 paper, but electrolysis appears in the production of materials topic, so I posted this here.

Calculate the voltage required to operate the cell shown as an electrolytic cell, showing relevant half equations in your working.

The diagram is just an iron electrode on the left and a copper electrode on the right, with all the usual things in a electrolytic cell (salt bridge, elctrolyte etc)

**

In a galvanic cell, the iron would be the anode, and the copper elctrode would be the cathode, correct? Shouldn't an electrolytic cell be exactly the reverse? Ie. Iron the cathode, and copper the anode?

Yet the answers say that the iron remains the anode.... what the hell!?!?!

Any help would be much much much appreciated! Many thanks in advance!

ur rite

In electrolytic cell, iron is the cathode and copper is the anode

 

[Gesus]

ur rite

In electrolytic cell, iron is the cathode and copper is the anode

???

its the hsc, they dont make mistakes
electrolytic is covers both electrolysis and galvanic reactions

 

[Xayma]

Electrolitic cells were removed from production of materials. They now just leave it in shipwrecks.

 

[boutfiddy]

i think they want you to work out the voltage reguired to make the galvanic cell work as an electrolytic cell ie voltage needed to reverse the reaction

 

[smallcattle]

oh ok... i think this question is abit tricky

it asked you to find the voltage REQUIRED to form a electrolytic cell..in order to form a electrolytic cell, an external emf must be applied and it must be greater than the emf that the cell is producing

so basically the question asked you to find the emf that this cell is producing as a GALVANIC CELL, therefore iron will be the anode where oxidation takes place


EDIT: late post..

 

[NichNich]

i think they want you to work out the voltage reguired to make the galvanic cell work as an electrolytic cell ie voltage needed to reverse the reaction

Thanks so much for all your help! I think I kinda get this question now lol, I'm a dumbass sorry.


**
The answer in the book (which is almost the same as boutfiddy's) is:

Fe --> Fe2+ + 2e- E = 0.44V
Cu2+ + 2e- ---> Cu E= 0.34V
Total E = 0.44+ 0.34 = 0.78V

To operate the cell as an electrolytic cell the current would need to be reversed. It would take more than 0.78 V in the opposite direction.

**

So I'm still kinda confused, when you want it as an electrolytic cell, wouldn't you put the Iron as the cathode, and Copper as the anode? So the above equations are reversed? And the total E = -0.78?

It says calculate it as an electrolytic cell... how do you know it wants the voltage from the galvanic reactions then reverse the voltage? And do I get it wrong if I put the equations above in reverse?

Ugh.. still confused, I'm an idiot...

Many thanks for the replies!!!

 

[kacca29]

it asked you to find the voltage REQUIRED to form a electrolytic cell..in order to form a electrolytic cell, an external emf must be applied and it must be greater than the emf that the cell is producing

so basically the question asked you to find the emf that this cell is producing as a GALVANIC CELL, therefore iron will be the anode where oxidation takes place

Right to get full marks you need to do exactly this, then as smallcattle says, say that the voltage required needs to be slightly higher than the emf produced as a galvanic cell. It won't matter which way you write your equations so long as you are clear about the final voltage required.

 

[smallcattle]

Thanks so much for all your help! I think I kinda get this question now lol, I'm a dumbass sorry.


**
The answer in the book (which is almost the same as boutfiddy's) is:

Fe --> Fe2+ + 2e- E = 0.44V
Cu2+ + 2e- ---> Cu E= 0.34V
Total E = 0.44+ 0.34 = 0.78V

To operate the cell as an electrolytic cell the current would need to be reversed. It would take more than 0.78 V in the opposite direction.

**

So I'm still kinda confused, when you want it as an electrolytic cell, wouldn't you put the Iron as the cathode, and Copper as the anode? So the above equations are reversed? And the total E = -0.78?

It says calculate it as an electrolytic cell... how do you know it wants the voltage from the galvanic reactions then reverse the voltage? And do I get it wrong if I put the equations above in reverse?

Ugh.. still confused, I'm an idiot...

Many thanks for the replies!!!

No you shouldnt write it in reverse. The diagram showed is a galvanic cell, so you do the half equation as it is in galvanic cell

the question asked for the voltaged required to forming an electrolytic cell if there is an external power source used, eg a power pack, and the voltage that power source will apply in order to make the electrolytic cell, which must greater than the voltage this galvanic cell is currently producing

 

[ilovechildren]

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