STEM PRACTICE AND EVIDENCE WORKBENCH
Calculate component mass percentages, reconstruct sample totals, and audit grouped composition evidence with visible denominators.
Review output
Load the worked example to inspect realistic inputs, or enter anonymous classroom or laboratory evidence. Results remain in this browser tab until you copy or download them.
Transparent method
Component mass percent equals component mass divided by total sample mass times one hundred. A supported group requires every learner percentage to match within tolerance and the sum of entered component masses to reconstruct the repeated total. This prevents individually correct divisions from hiding an incomplete or contradictory whole. Supported means both part-to-whole calculations and mass reconstruction agree for the entered evidence. It does not prove chemical composition is complete or accurate. Review sample basis, purity, hydration, conservation, measurement uncertainty, significant figures, omitted components, and whether the question asks mass percent, mole percent, elemental percent, or solution concentration.
Confirm the question, source, units, notation, response coding, model assumptions, and review threshold. Keep an unchanged copy of the original evidence.
Run the worked example, inspect every intermediate row, and compare it with a hand calculation, diagram, representation, or approved subject method.
Record the method, assumptions, units, classifications, and flagged rows. Verify the editable report independently before educational or laboratory use.
How to interpret the result
Use after masses are known and learners need to connect part-to-whole reasoning with percent composition. The diagnostic checks each component and the whole sample reconstruction. It does not infer a molecular formula, identify missing components, correct purity or hydration, convert between mass and moles, select atomic weights, or establish sample identity.
Sample A contains masses 20 and 30 out of total 50, giving 40 and 60 percent. Sample B contains 12 and 8 out of 20, giving 60 and 40 percent. The review sample has individually plausible 60 and 50 percent rows, but component masses sum to 11 while the stated sample mass is 10, so the group is flagged.
Component mass percent equals component mass divided by total sample mass times one hundred. A supported group requires every learner percentage to match within tolerance and the sum of entered component masses to reconstruct the repeated total. This prevents individually correct divisions from hiding an incomplete or contradictory whole.
Supported means both part-to-whole calculations and mass reconstruction agree for the entered evidence. It does not prove chemical composition is complete or accurate. Review sample basis, purity, hydration, conservation, measurement uncertainty, significant figures, omitted components, and whether the question asks mass percent, mole percent, elemental percent, or solution concentration.
Do not divide total mass by component mass, use different totals for rows in one sample, mix wet and dry basis, omit a component while expecting percentages to sum to 100, confuse percent composition with empirical formula subscripts, or round each row excessively. Preserve masses and audit their sum before interpreting percentages.
Learning boundary
This browser-local workbench applies only the disclosed rules. It cannot diagnose a learner, certify an experiment, or replace teacher, laboratory, and safety judgment.
Review checklist
Practical questions
No. Processing occurs in the current browser tab. Avoid personal information and retain authoritative records only in the approved school system.
No. It describes entered evidence under one disclosed rule. Review reasoning, uncertainty, access, and several evidence sources.
Treat it as an editable calculation aid. Show your own reasoning, cite required sources, and follow course and academic-integrity rules.
YOUR NIRMION
