Lesson: Electroplating and Coulometry

The atomic mass of an aqueous metal ion can be estimated by electroplating the metal onto a cathode and comparing the current in the electrolytic cell to the mass of metal deposited. Which of the following effects could not cause the atomic mass of the metal to be underestimated?

The atomic mass of an aqueous metal ion is estimated by electroplating the metal onto a cathode and comparing the current in the electrolytic cell to the mass of metal deposited. A student guesses that the oxidation state of the metal ion is +2. In reality, the oxidation state of the metal ion is +4. How does the calculated atomic mass compare to the true atomic mass?

An electrolytic cell is constructed from a copper plate anode and a copper mesh cathode immersed in an acidic aqueous solution of copper(II) sulphate. A constant current of 140 mA passes through the cell for 60.0 minutes. Calculate the increase in mass of the copper cathode.