Canonical lesson CHEMISTRY20-U4-L14 · outcome 20-D2.4k · depth CURRICULUM_BASELINE

Unit D: Quantitative Relationships in Chemical Changes - outcome 20-D2.4k

• Course: CHEMISTRY20 (SCN2796)
• Lesson ID: CHEMISTRY20-U4-L14
• Official outcome: 20-D2.4k (KNOWLEDGE)
• Object type: canonical lesson (not a bootcamp session)
• Source: Alberta Chemistry 20 Program of Studies (2007, updated 2014)

Official outcome text

explain the discrepancy between theoretical and actual yields

Learning intention

Meet 20-D2.4k with instruction, practice, and a check. The 10-session bootcamp does not replace this lesson.

Success criteria

1. Restate the outcome in classroom language without swapping in a different unit’s template.
2. Complete the worked-style task for this outcome.
3. Name the lab setting (classroom-supervised / teacher demo / dataset or simulation / forbidden).

Teaching

Percent yield = (actual/theoretical) × 100%. Discrepancy causes: incomplete reaction, side reactions, product left on glassware, moisture on a precipitate, weighing error, loss of gas. Percent yield > 100% usually means wet product or impurity, not “created mass.”

Worked example

Actual 4.35 g, theory 5.00 g → 87.0%. If a student reports 118%, look for wet crystals, not a miracle.

Guided practice

1. Actual 4.35 g, theory 5.00 g → percent yield. Explain one honest loss (transfer, incomplete reaction).
2. Near-miss: 118% yield celebrated as extra product. Mark wet crystals / scale error.

Independent practice

1. If actual 9.80 g and theory 10.0 g, percent and one discrepancy cause.
2. Two sentences: percent yield = actual/theoretical × 100%.
3. Do not invent a lab to force 100%.

Diagram / whiteboard

Approved diagram id chem20-stoich-mole-map - Mole map stoichiometry flow. Tutor may open the course whiteboard and display this id. Do not invent hazardous procedures on the board.

Checks for understanding

Use the formative evidence below as the exit check for this outcome. Correct the misconception named in this lesson before praising.

Misconception to repair

Blaming KMT particle volume for a low organic yield.

Safety and lab register

Setting: stoichiometry on balanced equations and provided mass/volume data. Live combustion or precipitation is teacher demo or school lab SOP only - never a home task. Titration (if run) is school burette, dilute reagents, goggles; otherwise use the provided titration-curve dataset. Forbidden: student-run flames, concentrating acids, tutor-invented yields labs. AI Tutor must not invent procedures.

Alberta Poison Control if a real exposure is occurring: 1-844-764-7669. The AI Tutor is not a poison centre.

Formative evidence

One percent-yield calculation plus one >100% diagnosis.

This is not a diploma. Mastery needs instruction + activity + check.

AI Tutor / human tutor

Ground on 20-D2.4k. No false praise. No invented procedures. No silent skip to a different unit. Human tutor if the student describes mixing bleach, tasting, or flames.

Provenance

Official POS wording from ALBERTA_SENIOR_HIGH_OFFICIAL_OUTCOMES.csv. Pack lesson written to replace Wave-4 contaminated canonical markdown.