How does temperature affect cell voltage in a galvanic cell?

Question

Specifically, a Cu/Zn cell.

Does an increase in temp mean an increase in voltage? Or is it the other way around ? (decrease in voltage)

Answer 1

http://en.wikipedia.org/wiki/Table_of_standard_electrode_potentials

gives E0(Cu2+/Cu) = +0.34 , E0(Zn2+/Zn) = -0.76

so under standard conditions Cu is reduced as it has the higher reduction potential, the cell reaction is therefore

Cu2+ + Zn -> Cu + Zn2+

cell EMF is given by the nernst equation

E = E0 - RT/nF lnQ

whether the EMF goes up or down with T depends on Q, the ratio of the activities:

Q = a(Zn2+) / a(Cu2+)

if a(Zn2+) > a(Cu2+), Q is greater than 1, lnQ is positive and E decreases with T. on the other hand if a(Zn2+) < a(Cu2+), E increases with T.

Answer 2

Zinc reacts wth sulphuric acid to, form sulphates and water so does copper., electrolysis is a physique of innovations in electrolytic chemistry and voltages are comments in electric powered technologies, the aspects Cu and Zn in electolytic chem produces a particular voltage, with copper as a greater helpful component than zinc on the grounds that of its residences, could you elect for a copper twine or a zinc twine? the respond is there... confirm it out.. the quantity of electrolyte won't impression the chemical reaction however the attention will.... one hundred cc of 10% elecgtrolyte is in no way 10cc of one hundred % electrolyte, offered it?