Mistake Master

Electrolysis and Faraday's Law

In electrolysis, the amount of substance produced is set by the charge passed, via Faraday's law. The ladder runs: charge = current × time (in seconds); moles of electrons = charge ÷ F (Faraday's constant); moles of metal = moles of electrons ÷ (electrons per ion); and finally grams = moles × molar mass.

UNIT 9 TOPIC 9.11 • ELECTROLYSIS AND FARADAY'S LAW FARADAY'S LAW Electrolytic cell power source (battery) + e⁻ e⁻ electron flow from power source Ag⁺ NO₃⁻ AgNO₃ (aq) anode (+) oxidation cathode (−) reduction Cathode: Ag⁺ + e⁻ → Ag(s) Faraday's law: charge → moles → mass q = I · t charge = current × time mol e⁻ = q / F charge ÷ Faraday constant F = 96,485 C·mol⁻¹ (charge per mole e⁻) Worked example — silver plating Given: I = 2.00 A, t = 965 s q = I·t = (2.00)(965) = 1930 C mol e⁻ = 1930 / 96,485 = 0.0200 mol e⁻ Ag⁺ + e⁻ → Ag (1 mol e⁻ per mol Ag) mass = 0.0200 mol × 107.87 g·mol⁻¹ mass of Ag deposited = 2.16 g More charge (larger I or longer t) → more Ag deposited. CED ANCHOR Electrolysis stoichiometry links charge → moles of e⁻ → mass: q = I·t, mol e⁻ = q / F, m = mol × M. Anode (+) oxidation · cathode (−) reduction · more charge → more product · F = 96,485 C per mole e⁻. AP Chemistry · Unit 9 · Applications of Thermodynamics
Electrolysis deposits or produces substance in proportion to charge passed. The Faraday ladder: charge = current × time (seconds); moles of electrons = charge ÷ F; moles of metal = moles of electrons ÷ (electrons per ion); grams = moles × molar mass.
Faraday Plating · Open the sandbox →

The traps drop or swap units along the ladder — taking moles of electrons as moles of metal (divide by the electron count per ion), using charge as moles (divide by F), plugging minutes in as seconds, or reporting moles where grams were asked (convert with molar mass). Carry each step through to the requested unit.

The work

3 ways in · any order
Lesson
Electrolysis & Faraday's Law

Faraday's law converts charge (current × time) to moles of electrons, then to moles of metal, then grams. The lesson climbs the ladder with correct units, then closes with a ten-scenario check.

Skill check · 10 scenarios
Diagnostic
10-item topic check

Ten items spanning the Topic 9.11 misconceptions: Faraday-ladder unit and step errors (electrons vs metal, charge vs moles, minutes vs seconds), and the final quantity reported in the wrong units.

Not started · 10 items · ~15 min
Targeted Practice
Drill a single misconception

Pick one of the failure modes you missed and drill it on its own. The round is adaptive: two correct in a row clears the misconception and moves you to the next.

Take the diagnostic to identify your misconceptions