CHEMISTRY · Multi-part · AP · Chemistry · Thermodynamics and Electrochemistry · Thermodynamics and Electrochemistry
Problem
In a classroom investigation, students electrolyze separate samples of 0.10molL−1AgNO3(aq) for exactly 6.0min while varying the current supplied by a constant-voltage power source. The teacher records the data shown below.
Current supplied (A)
Mass of Ag deposited (g)
0.25
0.099
0.50
0.199
0.75
0.298
1.00
0.401
Assume silver ions are the only species reduced and that the deposition reaction is 100% efficient.
Faraday constant: F=9.6485×104Cmol−1
(a) Using the numerical data, identify the mathematical relationship that best describes how the mass of silver deposited depends on the current supplied. Support your answer with evidence from the table.
(b) Provide a particulate-level explanation for why the observed relationship in part (a) should be expected for this electrolytic reaction.
(c) Derive an algebraic expression that relates the mass m of Ag deposited during electrolysis to the current I, the elapsed time t, the molar mass MAg, and the Faraday constant F. Clearly define every symbol used.
(d) A graph of deposited mass versus current for the experiment would have a constant slope. Determine the numerical value of that slope and interpret its physical meaning in the context of silver deposition.