CHEMISTRY · Multi-part · AP · Chemistry · Thermodynamics and Electrochemistry · Thermodynamics and Electrochemistry
Problem
During an electrolysis experiment, a constant current of 2.50 A is passed for 35.0 min through an aqueous solution that contains an unknown divalent metal ion M2+. The mass of the cathode increases by 1.70 g as the metal plates out.
Assume the Faraday constant is 96 485 C mol−1 of electrons.
Possible identities for the metal include Zn, Ni, and Cu.
(a) Calculate the total electrical charge that passed through the cell during the 35.0 min interval.
(b) Determine the number of moles of electrons transferred to the cathode.
(c) Using the measured mass gain of the cathode, calculate the experimental molar mass of the metal.
(d) Based on your result in part (c), identify the most probable metal among the three possibilities and briefly justify your choice.