Canonical lesson CHEMISTRY20-U4-L17 · outcome 20-D2.7k · depth CURRICULUM_BASELINE

Unit D: Quantitative Relationships in Chemical Changes - outcome 20-D2.7k

• Course: CHEMISTRY20 (SCN2796)
• Lesson ID: CHEMISTRY20-U4-L17
• Official outcome: 20-D2.7k (KNOWLEDGE)
• Object type: canonical lesson (not a bootcamp session)
• Source: Alberta Chemistry 20 Program of Studies (2007, updated 2014)

Official outcome text

identify equivalence points on strong monoprotic acid-strong monoprotic base titration curves and differentiate between the indicator end point and the equivalence point

Learning intention

Meet 20-D2.7k 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

Equivalence point: stoichiometric moles of acid = moles of base (net H3O+ and OH− matched). For strong-strong, pH = 7 at 25 °C. End point: the indicator colour change. They are not identical; a well-chosen indicator makes them close enough for Chem 20.

Worked example

If phenolphthalein turns at a drop past 25.05 mL and equivalence is 25.00 mL, the end point is slightly after equivalence. Report volumes honestly.

Guided practice

1. Equivalence 20.00 mL; indicator turns at 20.08 mL. Name both points and the volume error.
2. Near-miss: reporting the end point as the equivalence without comment. Mark it.

Independent practice

1. If the turn is 0.05 mL early, is [unknown] high or low?
2. Two sentences: stoichiometric equivalence vs observable end point.
3. Honest recording of volumes.

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

Using end point and equivalence as synonyms with no distinction.

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

Define both terms on one titration story with numbers.

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

AI Tutor / human tutor

Ground on 20-D2.7k. 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.