Chemical Forums
Chemistry Forums for Students => High School Chemistry Forum => Topic started by: crustd on May 17, 2021, 11:45:50 AM
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Does the voltage change with temperature if the concentration of the solutions is the same in the galvanic cell? Based on the Nernst Equation, if the reaction quotient is 1, lnQr becomes 0, and thus the voltage equals standard cell potential regardless of temperature. Is this correct? I performed an experiment where I changed the temperature of a daniell cell, where both solutions were at 0.5 moldm3, and the results showed a slight increase in voltage as temperature increased. Is this due to the increase in resistance as temperature increases?
If I want to see how the nernst equation models the change of voltage in a galvanic cell, I'd have to have a reaction quotient that is not 1, is that correct? What would be the relationship between temperature and voltage if performed at a reaction quotient above 1?
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It will, check the original formula for Nernst equation you will find the temperature in it.
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It will, check the original formula for Nernst equation you will find the temperature in it.
I'm sorry, but when the reaction quotient is 1, doesn't lnQ become 0? Doesn't that get multiplied with the RT part of the equation, thus making whatever the temperature is 0 anyway?
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Then you have only the standard potential. There is no Temperature.
You was talking about the Daniel element and you have solutions of zinc and copper sulfate, which change during process.
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There is a temperature dependence of the standard cell potential; see e.g. https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Book%3A_Physical_Chemistry_(Fleming)/10%3A_Electrochemistry/10.04%3A_Entropy_of_Electrochemical_Cells