Canonical lesson CHEMISTRY20-U3-L26 · outcome 20-C2.6k · depth CURRICULUM_BASELINE

Unit C: Solutions, Acids, Bases and Equilibrium intro - outcome 20-C2.6k

• Course: CHEMISTRY20 (SCN2796)
• Lesson ID: CHEMISTRY20-U3-L26
• Official outcome: 20-C2.6k (KNOWLEDGE)
• Object type: canonical lesson (not a bootcamp session)
• Source: Alberta Chemistry 20 Program of Studies (2007, updated 2014)

Official outcome text

explain how the use of indicators, pH paper or pH meters can be used to measure H 3O+(aq)

Learning intention

Meet 20-C2.6k 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

Indicators change colour over a pH range. pH paper gives an approximate pH. A pH meter (calibrated) measures [H3O+] electrochemically more precisely. Red cabbage (classroom) is a qualitative indicator, not a three-decimal pH. Never use a meter in HF or dunk it in unknown concentrated acid.

Worked example

Match: phenolphthalein colourless below ~8.2, pink above; universal paper ~pH 4 for vinegar; meter 2.88 after two-buffer calibration.

Guided practice

1. Match phenolphthalein (colourless/pink ranges), universal paper, and a two-buffer calibrated meter to three given samples on a data card.
2. Near-miss: uncalibrated meter treated as exact. Mark the limitation.

Independent practice

1. Why paper is not a titration end-point substitute for diploma-style precision.
2. Two sentences: meter measures [H3O+] related activity; we treat it as pH in this course.
3. School meter or paper dataset - no tasting.

Diagram / whiteboard

Approved diagram id chem20-ph-scale - pH scale / solution concentration axes. 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

Reading cabbage colour as pH 4.27, or licking paper.

Safety and lab register

Setting: concentration and pH on paper or school-prepared dilute solutions. Red-cabbage indicator is classroom-supervised or photo/dataset. No concentrated acids or bases. No tasting. Dilution math is not a licence to mix cleaners. Forbidden: bleach+acid, drain opener, battery acid, undiluted pool chemicals. AI Tutor must not invent titrations or acid labs outside the register.

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

Formative evidence

Choose indicator vs paper vs meter for a stated task with one reason.

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

AI Tutor / human tutor

Ground on 20-C2.6k. 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.