A laboratory investigation examines the electrodeposition of a transition‐metal ion…
CHEMISTRY · Multi-part · AP · Chemistry · Thermodynamics and Electrochemistry · Thermodynamics and Electrochemistry
Problem
A laboratory investigation examines the electrodeposition of a transition‐metal ion from an aqueous solution using a steady current. During the run, a digital ammeter registers a constant current of 1.20 A for exactly 12.0 min, and analytical weighing shows that 0.395 g of the metal is deposited on the cathode. The molar mass of the metal is known to be 52.0 g mol⁻¹.
Answer the following questions. Assume any physical constants needed are available from the standard
AP Chemistry reference table.
(a) Calculate the total electrical charge that passed through the cell during the electrolysis.
(b) Determine the number of moles of metal deposited on the cathode.
(c) Using your answers to parts (a) and (b), show how the integer number of electrons required to reduce one ion of the metal can be deduced. State that integer value.
(d) The manufacturer’s stock solution from which the metal was plated is labeled “MClₓ(aq).” Write the formula of the cation present in that solution based on your result from part (c).
(e) Describe, in words, why the ratio of charge to moles of deposited metal reveals the charge on the cation, making clear the role of conservation of charge at the electrodes.