Electrolysis stoichiometry calculator

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About this MicroSim

Radio buttons let students choose which quantity to solve for (mass deposited, required time, or required current). The input panel covers metal selection, molar mass, electrons per ion, current, time, and target mass as needed. Pressing Calculate walks through the Faraday chain with four animated boxes: total charge, moles of electrons, moles of metal, and mass. A mini electrolytic cell diagram on the right adds or removes particles in sync with the computed mass, and a reset button clears the form.

How to use

1. Pick the solve-for mode (mass, time, or current) at the top.
2. Select a metal from the dropdown or choose Custom to enter molar mass and electrons per ion.
3. Enter the known values for current (A), time (min), and target mass (g). Only relevant fields are enabled for the chosen mode.
4. Click Calculate to highlight each Faraday step and display the result; the answer card shows both the numerical value and unit.
5. Press Reset to clear all fields and hide the step boxes.

Learning goals (Step 1)

Item	Details
Subject area	Chemistry - electrochemistry
Grade band	AP Chemistry / introductory college
Learning objective	Students will apply Faraday's laws to convert between charge, moles of electrons, moles of substance, and deposited mass or required current/time.
Bloom's level	Apply
Duration	10-12 minutes
Prerequisites	Redox half-reactions, stoichiometry, unit conversions (A = C/s)
Assessment ideas	Provide two electrolytic scenarios (e.g., Cu plating mass and Ag plating time) and have students document the calculator steps and reasoning.

Instructional design review (Step 1.5)

Question	Target	Decision
Single learning objective?	Yes	Focused on Faraday-law stoichiometry.
Number of controls	1-5	Four rows (radio buttons + dropdown, two numeric input rows, reset/calc buttons).
Progressive disclosure	Needed	Only relevant input fields and calculation steps are enabled per mode.
Cognitive load	Managed	Step-by-step boxes and visual cell keep the workflow linear.
Accessibility	Required	Controls live beneath the canvas with >16 px text and clear labels.

Control inventory

#	Control type	Label text	Value format	Row
1	Radio buttons	Solve for	Mass, time, or current	1
2	Dropdown + optional inputs	Metal selection / custom parameters	Predefined metals (Cu, Ag, Au, Al, Fe) or custom molar mass & electrons	2
3	Numeric inputs	Current (A), Time (min), Target mass (g)	Decimal values	3
4	Buttons	Calculate / Reset	Buttons	4

Layout planning (Step 2.5)

• Number of control rows: 4
• controlHeight = (4 x 60) + 40 = 280 px
• drawHeight = 540 px (title + diagram + step boxes)
• canvasHeight = 540 + 280 = 820 px
• iframeHeight = 820 + 2 = 822 px
• sliderLeftMargin = 240 px (150 px label + 90 px value field)
• margin = 26 px

Position assignments

// Row 1 (solve-for radio group)
controlRows[0].position(margin, drawHeight + 25);
// Row 2 (metal dropdown + custom inputs)
controlRows[1].position(margin, drawHeight + 95);
// Row 3 (current/time/mass inputs)
controlRows[2].position(margin, drawHeight + 165);
// Row 4 (Calculate / Reset buttons)
controlRows[3].position(margin, drawHeight + 235);

Label/value alignment

labelSpan.style('width', '150px');
valueSpan.style('width', '90px');
slot.style('width', '280px');

Lesson plan

1. Demo (3 min): Instructor deposits copper by entering current and time; emphasize each Faraday step.
2. Swap modes (5 min): Students solve for time needed to plate a specific mass of silver, documenting the inputs and workflow.
3. Challenge (3 min): Groups create a custom ion (e.g., Al3+) and predict the plating mass for a given charge, checking with the sim.

References

1. Petrucci, Harwood, Herring. General Chemistry, 9th ed., Pearson, 2007 — Electrolysis and Faraday's laws.
2. Tro, N. J. Chemistry: A Molecular Approach, 5th ed., Pearson, 2020 — Worked examples on electroplating stoichiometry.