calculate the potential of a silver electrode in contact with the following: the solution that results from mixing 25ml of 0.05M KBr with 20mL of 0.1M Ag+
To calculate the potential of a silver electrode in contact with the given solution, we will use the Nernst equation. The Nernst equation relates the potential of an electrode to the concentration of the species involved in the redox reaction and the standard electrode potential.
Here are the steps to calculate the potential:
1. Determine the balanced redox reaction occurring at the silver electrode. In this case, it is the reduction of Ag+ ions.
2. Write the balanced equation for the redox reaction. The balanced equation for the reduction of Ag+ is: Ag+ + e- → Ag.
3. Find the standard electrode potential, E°, for the given redox reaction. The standard electrode potential for Ag+/Ag half-cell is 0.799 V.
4. Calculate the concentration of Ag+ ions in the solution using the given information. We have 20 mL of a 0.1 M Ag+ solution, so the number of moles of Ag+ ions is:
(20 mL) x (0.1 mol/L) = 2 mmol Ag+
Converting mmol to mol:
2 mmol Ag+ = 0.002 mol Ag+
5. Calculate the concentration of Br- ions in the solution. We have 25 mL of a 0.05 M KBr solution, so the number of moles of Br- ions is:
(25 mL) x (0.05 mol/L) = 1.25 mmol Br-
Converting mmol to mol:
1.25 mmol Br- = 0.00125 mol Br-
6. Substitute the calculated concentrations and the standard electrode potential into the Nernst equation:
E = E° - (RT/nF) * ln([Ag+]/[Br-])
Where:
E is the potential of the silver electrode,
E° is the standard electrode potential (0.799 V),
R is the gas constant (8.314 J/(mol·K)),
T is the temperature in Kelvin (usually room temperature, around 298 K),
n is the number of electrons transferred (in this case, it's 1),
F is Faraday's constant (96485 C/mol),
[Ag+] is the concentration of Ag+ ions, and
[Br-] is the concentration of Br- ions.
Plug in the values into the Nernst equation to calculate the potential of the silver electrode.