NextStep FL NS 3 C/P #36

[jeep1010]

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The answer description states: "C is correct. The passage states that the cell is meant to act like a galvanic cell, meaning that it proceeds in a spontaneous fashion."

Can someone possibly explain how the passage hints at the electrochemical cell being galvanic? vs. How would I know if it is electrolytic?

@NextStepTutor_2
@NextStepTutor_3

 

[NextStepTutor_3]

Hi there, great question!

Remember, a galvanic cell generates a current, and can thus be used to power other processes. In contrast, an electrolytic cell requires a power source to proceed at all (since it is nonspontaneous).

So a simple question you can ask yourself when confronted with an electrochemical cell is, "Is a separate power source provided?" If so, you're likely powering a nonspontaneous reaction, so you're dealing with an electrolytic cell. If not, you're probably looking at a galvanic cell.

The passage also gives several more hints as to the galvanic nature of this cell:

In the first sentence, it mentions that biostarch batteries "convert the energy stored in starch bonds into electrical energy." This implies that our battery is producing an electrical current on its own. Similarly, the caption for Figure 1 references "generating electricity." Later in the passage, we see that starch batteries "generate sufficient power for commercial use." At this point, we know for certain that our battery is galvanic, since an electrolytic cell would not generate power - it would require external power to do anything at all.

Good luck with your studies!

 

[aldol16]

Can someone possibly explain how the passage hints at the electrochemical cell being galvanic? vs. How would I know if it is electrolytic?

The easiest way in general is to calculate whether the cell potential is positive or negative.

 

[NextStepTutor_3]

@aldol16 , completely agree. The problem with doing that for this particular passage was that they gave the reduction potentials of both species involved, but they didn't tell us which would reduce and which would oxidize - making us unable to calculate the cell potential without already knowing whether it was a galvanic or an electrolytic cell. So we needed to resort to passage clues and general reasoning instead.

 

[aldol16]

@aldol16 , completely agree. The problem with doing that for this particular passage was that they gave the reduction potentials of both species involved, but they didn't tell us which would reduce and which would oxidize - making us unable to calculate the cell potential without already knowing whether it was a galvanic or an electrolytic cell. So we needed to resort to passage clues and general reasoning instead.

Ah, so they basically had to determine, using context, whether to set up the cell electrolytically or not.