Chemistry: Electrochemistry Flashcards
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The Nernst equation at 25 °C is E = E° − (0.0592/n) log Q. As Q increases, the cell potential:
Answer: Decreases
A larger Q makes the log term larger, subtracting more from E° and lowering E.
When an electrochemical cell reaches equilibrium, the cell potential E equals:
Answer: 0 V
At equilibrium no net reaction occurs, so the measured cell potential is zero.
For a cell with n = 2 and E° = +0.46 V, what is log K at 25 °C?
Answer: About 15.5
log K = nE°/0.0592 = (2 × 0.46)/0.0592 ≈ 15.5.
Increasing the concentration of reactant ions in the cathode compartment will generally:
Answer: Increase the cell potential
More cathode reactant lowers Q, which raises E according to the Nernst equation.
A concentration cell generates voltage because of a difference in:
Answer: Ion concentration between the two half-cells
A concentration cell uses identical electrodes but differing ion concentrations to produce potential.
In a concentration cell, the half-cell with the lower ion concentration acts as the:
Answer: Anode
The dilute side undergoes oxidation to raise its ion concentration, making it the anode.
What is the standard temperature assumed when using the 0.0592/n form of the Nernst equation?
Answer: 298 K (25 °C)
The constant 0.0592 V is derived assuming 298 K.