electrochem experiment...SOS! (1 Viewer)

[batigol]

its like this, i set up a galvanic cell and i varied the width of the copper electrode (5 widths were used) while keeping the other electrode unchanged. the results showed that the voltage output was always a constant no matter how the width of the copper electrode changed.

i was pretty confident coz i tried copper with 3 other electrodes and found the same result. then my teacher came in and said he was pretty sure it was wrong ie. the voltage should increase with increasing widths.

there are 2 possible explanation for the way we each of us thinks. for me i said that since the voltage for 2 particular electrodes (as found in the standard table) gives energy to the electrons, that energy is fixed. increasing width means increasing number of electrons there are. but this doesnt matter coz the same energy will be given to them anyway, so the current should be the same and hence a constant voltage.

my teacher said something along the line of: if the width increases, theres more surface area for the reaction to happen, so there should be more voltage. he also said that it 'doesnt make sense' to vary only the width of one electrode only, so i should have changed the width of both to see the result.

btw, does the concentration of the electrolyte affect the voltage? are electrode potential in the standard table for solutions of 1M only ( i used 0.1M, didnt think of concentration)

so, i think i sound like a chem problem, but this is an actual experiment lol, anyone have any ideas or have done something similar? thank u

 

[DraconisV]

well mabye the reaction between the electrodes is not happening at a good speed for the resistance of the thinner wires to get calculated in. If u sped up the reactions then with the thinner wire you would see a less voltage as there is more resistance and also the thin wire will get hot, from the resistance.

Thats my 2 cents worth.

Hope i helped

p.s. i did resistance in phys today it was fun

 

[Dreamerish*~]

Yes, the concentration of the electrolytes must be the same, I'm pretty sure it was 0.1M, but don't take my word for it.

Well, seeing as your teacher is a teacher , I would put my bet on him. It is true that a larger surface area may affect the reaction rate, and you should be changing the widths of both electrodes to see the difference.

The voltage should remain the same, as calculated from the E^ø table. It simply makes no sense for the voltage to change according to the size of the electrodes. When the strips are wider, providing more surface area, the reaction rate increases. I'm not 100% what effect this would have on the Galvanic cell, though.

Hope it helped.