The dependence of cell potential on concentration, is described by the Nernst Equation:To confirm the dependence of the data below on the Nernst equation and to determine the E° M2+/M and thus identify the metal ion, you are required to draw two graphs using two sheets of suitable A4 graph paper.Graph 1: Plot Ecell versus [M2+].Graph 2 : Plot Ecell versus a suitable variable to obtain a straight line and obtain E° from this graph.Choose an appropriate scale for plotting the following data.[M2+] molL-10.050.0010.00010.000020.0000050.0000001EM2+ M-0.438-0.489-0.518-0.539-0.557-0.607The value of Eo for this system is:Group of answer choices-0.23 V-0.66 V0.26 V-0.40 VNone of the above
Question
The dependence of cell potential on concentration, is described by the Nernst Equation:To confirm the dependence of the data below on the Nernst equation and to determine the E° M2+/M and thus identify the metal ion, you are required to draw two graphs using two sheets of suitable A4 graph paper.Graph 1: Plot Ecell versus [M2+].Graph 2 : Plot Ecell versus a suitable variable to obtain a straight line and obtain E° from this graph.Choose an appropriate scale for plotting the following data.[M2+] molL-10.050.0010.00010.000020.0000050.0000001EM2+ M-0.438-0.489-0.518-0.539-0.557-0.607The value of Eo for this system is:Group of answer choices-0.23 V-0.66 V0.26 V-0.40 VNone of the above
Solution
The Nernst equation is given by:
E = E° - (RT/nF) * ln(Q)
where: E is the cell potential, E° is the standard cell potential, R is the gas constant, T is the temperature in Kelvin, n is the number of electrons transferred in the redox reaction, F is the Faraday constant, and Q is the reaction quotient, which is the ratio of the concentrations of the products to the reactants.
In this case, we can simplify the Nernst equation to:
E = E° - (0.0592/n) * log([M2+])
since we are at room temperature (25°C or 298K), and we are dealing with a reduction reaction where n=2.
For Graph 1: Plot Ecell versus [M2+]. You can plot the given [M2+] values on the x-axis and the corresponding Ecell values on the y-axis. This graph will not be a straight line, but it will show the dependence of Ecell on [M2+].
For Graph 2: Plot Ecell versus log([M2+]). To obtain a straight line, you can plot the log([M2+]) values on the x-axis and the corresponding Ecell values on the y-axis. The slope of this line will be -0.0592/n, and the y-intercept will be E°.
To find E°, you can use the equation of the line from Graph 2. The y-intercept of the line is E°.
After plotting the graphs and finding E°, you can compare the calculated E° with the given options to identify the metal ion.
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