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How does temperature affect voltage in a galvanic cell?

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Last updated date: 25th Feb 2024
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IVSAT 2024
Answer
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Hint: Standard electrode potential is specified as the voltage potential under standard conditions at temperature $25^\circ C$ and concentration 1.00 mol/L, as the voltage of the galvanic cell is dependent on both temperature and the concentration of electrolyte.

Complete step by step answer:
Galvanic cells are the electrochemical cell used to convert chemical energy into electrical energy, by redox reactions. We can understand the galvanic cell with the help of zinc/copper galvanic cell, the galvanic cell consists of a zinc electrode dipped in a solution of zinc sulfate, a copper electrode dipped in a solution of copper sulfate, a salt bridge which connect the two solutions, and a wire which connects the two electrodes. At the anode oxidation reaction takes place. Anode is a negative electrode, zinc is oxidised to zinc ions $Z{n^{2 + }}$. At the cathode reduction takes place. It is a positive electrode. Here, copper ions $C{u^{2 + }}$ is reduced to copper metal. The salt bridge allows negatively charged anions to migrate toward the anode, completing the circuit and allows the positively charged cations to migrate toward the cathode, which balances the charge imbalance created by the movement of anions. The sulfate ion $SO_4^{2 - }$ is a spectator ion, therefore it does not react.
The oxidation half reaction is shown below.
$Zn(s) \to Z{n^{2 + }}(aq) + 2{e^ - }$
The reduction half reaction is shown below.
$C{u^{2 + }}(aq) + 2e \to Cu(s)$
The overall reaction is shown below.
$Zn(s) + C{u^{2 + }}(aq) \to Z{n^{2 + }}(aq) + Cu(s)$
The Nernst equation is applied to determine the voltage potential of a galvanic cell at nonstandard temperatures and concentrations.
The Nernst equation is given as shown below.
${E_{cell}} = E_{Cell}^0 - \left( {\dfrac{{RT}}{{zF}}} \right) \times \ln ({Q_r})$
Where,
${E_{Cell}}$ is the voltage of the cell at non-standard conditions
$E_{Cell}^0$ standard cell potential
R is the universal gas constant
T is the temperature in Kelvin
z is the number of moles of electrons transferred in the reaction.
F faraday constant.
${Q_r}$ is the reaction quotient
From the experiment performed using the Nernst equation, it was hypothesized that the voltage produced by the galvanic cell would decrease as the temperature increases. The voltage and the temperature is inversely proportional to each other.

Note: During the experiment the temperatures below room temperature were not tested, to reduce the time taken in each trial. The maximum temperature was from$50^\circ C$ and $70^\circ C$, so the temperature range tested was large enough to precisely determine the relationship between temperature and voltage.

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