Galvanic Cell Current

[sniderwes]

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I know that as the reaction proceeds in galvanic cell batteries and goes towards equilibrium, cell potential/voltage decreases until it hits 0 and you have a dead battery.

What about the current? Does it stay constant the whole time, and then becomes 0 once it is a dead cell?

 

[Czarcasm]

I know that as the reaction proceeds in galvanic cell batteries and goes towards equilibrium, cell potential/voltage decreases until it hits 0 and you have a dead battery.

What about the current? Does it stay constant the whole time, and then becomes 0 once it is a dead cell?

Apparently not if flashlights gets dimmer and dimmer as the batteries get old. I think for the purpose of the MCAT though, for simplicity, it would be safe to assume that current is constant within a given period of time. In actuality, I don't think that's really true. I believe over time it would slow down until it reaches a halt. The reaction rate is dependent on how much of reactant is being consumed within a given time period. Because that's changing, then clearly the current should be as well (since electron flow is a function of reactant consumption/oxidation). This is strange though because at equilibrium, we usually consider the rate to be constant in both directions. But in this instance, reaching equilibrium would halt current flow entirely since there's no longer a potential difference between both cells.