Canonical lesson CHEMISTRY20-U3-L27 · outcome 20-C2.7k · depth CURRICULUM_BASELINE

Unit C: Solutions, Acids, Bases and Equilibrium intro - outcome 20-C2.7k

• Course: CHEMISTRY20 (SCN2796)
• Lesson ID: CHEMISTRY20-U3-L27
• Official outcome: 20-C2.7k (KNOWLEDGE)
• Object type: canonical lesson (not a bootcamp session)
• Source: Alberta Chemistry 20 Program of Studies (2007, updated 2014)

Official outcome text

define Arrhenius (modified) acids as substances that produce H3O+(aq) in aqueous solutions and recognize that the definition is limited

Learning intention

Meet 20-C2.7k 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

Modified Arrhenius acid: a substance that produces H3O+(aq) in water. HCl + H2O → H3O+ + Cl−. Limitation: NH4+ solutions are acidic but NH4Cl is not “producing H3O+ by Arrhenius HCl-style ionization” in the simple molecular-acid picture; organic acids and acids that need water specified show the definition’s edge. Chem 20 notes the limit without requiring full Brønsted mastery of every case.

Worked example

HNO3(aq) fits cleanly. CO2(aq) producing carbonic acid is an indirect path. The definition is water-centred, so it does not describe acid-base in other solvents.

Guided practice

1. Show HCl(g) → H3O+(aq) in water. Contrast why this definition is limited in non-water solvents.
2. Near-miss: CO2 called an Arrhenius acid without the carbonic-acid path. Qualify it.

Independent practice

1. HNO3 as a clean fit.
2. Two sentences: hydronium production in water.
3. Limitation: solvent must be water in this definition.

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

Saying Arrhenius acids “donate protons” as if that were the Arrhenius wording (that is Brønsted).

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

Definition + one clean example + one limitation sentence.

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

AI Tutor / human tutor

Ground on 20-C2.7k. 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.