Physical Science: Chemistry — Student & parent guide
Parent teaching plan · 36 weeksReading libraryPhysical Science: Chemistry contains 46 focused units across 12 chapters. Four explained visual parts per unit connect observations, particle/structure models, calculations and evidence limits. Each chapter has a background reading, investigation, review and quiz, supported by a detailed parent plan and full midterm, sample and final papers.
A suggested lesson routine
- Read the opening phenomenon and defined terms; make a first model or prediction.
- Study the core explanation and Parts 1–2 with their labeled figures and reasoning checks.
- Study Parts 3–4, work through examples with answers covered, then attempt the whole-unit and changed independent cases.
- Check units, species, conservation and assumptions; explain a correction and revise the opening account.
- Use separately scheduled investigations and assessments to connect ideas; extend difficult topics from actual feedback.
The linked 36-week plan schedules 180 sessions: 110 unit-study sessions (two core sessions per unit plus a third for 18 demanding topics), 24 dedicated investigation sessions, 12 chapter reviews, 12 quizzes, nine exam/correction/portfolio allocations and 13 consolidation sessions. Most sessions are 50–60 minutes. The complete 60-minute midterm follows its six-chapter scope in Week 20. The sample is a full 90-minute sitting in Week 35 paired with about 30 minutes of corrections; the final is one continuous 180-minute sitting in Week 36. This is a flexible authored home-study route, not validated mastery timing or school laboratory certification.
Keep a science notebook
Keep dated notes, definitions, diagrams, worked problems, corrected errors, and evidence records. Record supplied versus measured data honestly. Learning progress is saved on this device; keep a separate notebook as a durable study record.
Use assessments well
Chapter quizzes mix automatically checked questions and written responses requiring a learner/parent comparison. Use the handbook cumulative assessment and discussion rubric to judge reasoning across the course, rather than relying only on repeated fixed quizzes. Exam papers and parent keys are available from the Course exams links.
Adjust the support
A parent can use the explicit worked solutions and criteria without needing to invent missing explanations. Students should attempt questions before revealing answers. Break a long unit into two or more sessions and return to its prerequisite notes as needed.
School laboratory requirements
the district's directory specifies 1,200 laboratory minutes, including three NYS-mandated investigations, for its Regents chemistry and physics courses. These home activities and supplied-data analyses support learning but do not certify that supervised requirement. Confirm actual examination eligibility and mandated laboratory arrangements with the responsible school or assessment authority.
Reference tools
- NYSED 2025 Chemistry reference tables
- NGSS high-school physical science expectations
- OpenStax Chemistry 2e: optional full-text reference
- OpenStax: pH and pOH reference
- OpenStax: free energy reference
- OpenStax: galvanic cells
- OpenStax: formal charges and resonance
- OpenStax: radioactive decay
Start here: readiness and recovery
Complete the six questions below before opening the worked answers. This is a diagnostic, not a grade. If conversions, ratios, or algebra are uncertain, spend several sessions practicing those skills using the measurement unit and the examples in this guide. Chemistry learners should also check scientific notation, logarithms, and rearranging equations before concentration, pH, gas, and equilibrium calculations.
Keep a correction log: name the missing skill, write one worked example in your own words, solve a changed version, and explain the result aloud. Return to the course when you can do the prerequisite without copying.
Question 1
Convert 250 mL to liters and 2.5 kg to grams.
Worked solution and marking guidance
Use 1000 mL per liter and 1000 g per kilogram.
0.250 L; 2500 g.
- 1 point: select a valid relationship, mechanism, or model.
- 1 point: show correct calculation or evidence-based reasoning.
- 1 point: give a correct conclusion with units and stated conditions.
Question 2
Solve 3x/2=9.
Worked solution and marking guidance
Multiply both sides by 2 and divide by 3.
x=6.
- 1 point: select a valid relationship, mechanism, or model.
- 1 point: show correct calculation or evidence-based reasoning.
- 1 point: give a correct conclusion with units and stated conditions.
Question 3
Calculate (2×10³)(3×10⁻²).
Worked solution and marking guidance
Multiply coefficients and add exponents: 6×10¹.
60.
- 1 point: select a valid relationship, mechanism, or model.
- 1 point: show correct calculation or evidence-based reasoning.
- 1 point: give a correct conclusion with units and stated conditions.
Question 4
Count atoms represented by 2Ca(OH)₂.
Worked solution and marking guidance
The coefficient multiplies the whole formula; parentheses multiply both O and H.
2 Ca, 4 O, and 4 H.
- 1 point: select a valid relationship, mechanism, or model.
- 1 point: show correct calculation or evidence-based reasoning.
- 1 point: give a correct conclusion with units and stated conditions.
Question 5
A particle has 12 protons and 10 electrons. What is its charge?
Worked solution and marking guidance
Subtract negative-charge count from positive-charge count.
+2.
- 1 point: select a valid relationship, mechanism, or model.
- 1 point: show correct calculation or evidence-based reasoning.
- 1 point: give a correct conclusion with units and stated conditions.
Question 6
What makes an evidence-based claim stronger than a guess?
Worked solution and marking guidance
Identify specific observations, a mechanism, and possible alternatives.
A supported claim cites repeatable evidence, explains it through a tested model, and states uncertainty.
- 1 point: select a valid relationship, mechanism, or model.
- 1 point: show correct calculation or evidence-based reasoning.
- 1 point: give a correct conclusion with units and stated conditions.
A 36-week study plan
The detailed linked weekly route gives each unit two core sessions, plus a third for 18 selected calculation/modeling topics. It reserves separate investigation, review, quiz and correction time rather than assuming 46 three-session units leave enough room for every assessment.
The midterm in Week 20 covers its six completed chapters. The complete sample is in Week 35, and Week 36 reserves one continuous 180-minute final plus marking and portfolio discussion. Extend or redistribute sessions when actual understanding requires it; no supplied-data route certifies laboratory eligibility.
| Weeks | Chapter | Units | Study work |
|---|---|---|---|
| 1–2 | Investigating Matter | 2 | Two core sessions/unit; selected third sessions, two-session investigation, review and quiz. |
| 3–6 | Atoms, Electrons & Periodicity | 6 | Two core sessions/unit; selected third sessions, two-session investigation, review and quiz. |
| 7–10 | Bonding, Formulas & Molecular Structure | 6 | Two core sessions/unit; selected third sessions, two-session investigation, review and quiz. |
| 11–13 | Reactions, Moles & Composition | 5 | Two core sessions/unit; selected third sessions, two-session investigation, review and quiz. |
| 14–16 | Stoichiometry & Yield | 3 | Two core sessions/unit; selected third sessions, two-session investigation, review and quiz. |
| 17–20 | States of Matter & Gases | 5 | Two core sessions/unit; selected third sessions, two-session investigation, review and quiz. Complete midterm and correction in Week 20. |
| 21–22 | Solutions & Dissolved Particles | 3 | Two core sessions/unit; selected third sessions, two-session investigation, review and quiz. |
| 23–25 | Acids, Bases & Titration | 4 | Two core sessions/unit; selected third sessions, two-session investigation, review and quiz. |
| 26–27 | Chemical Energy & Thermodynamics | 3 | Two core sessions/unit; selected third sessions, two-session investigation, review and quiz. |
| 28–30 | Rates & Equilibrium | 3 | Two core sessions/unit; selected third sessions, two-session investigation, review and quiz. |
| 31–33 | Redox, Cells & Nuclear Chemistry | 4 | Two core sessions/unit; selected third sessions, two-session investigation, review and quiz. |
| 34–36 | Organic Chemistry & Material Design | 2 | Two core sessions/unit; selected third sessions, two-session investigation, review and quiz. Complete sample in Week 35; final and portfolio in Week 36. |
How to solve an unfamiliar problem
- Draw the situation or system and identify what is being asked.
- List given values with units; state unknowns, directions, and conditions.
- Select a relationship and explain why its assumptions fit.
- Rearrange before substituting; carry units through the calculation.
- Keep extra digits during work and round appropriately at the end.
- Check magnitude, sign, dimensions, conservation, and whether the result answers the question.
- For a written claim, cite specific evidence, explain the mechanism, and name a limitation or alternative.
Reference relationships
These reminders accompany the unit explanations; they are not substitutes for defining conditions. A symbol can have different meanings in different equations, so write its meaning and unit in your notebook.
| Quantity | Relationship | Use / conditions |
|---|---|---|
| Density | ρ=m/V | Mass and volume in consistent units |
| Amount | n=m/Mm; N=nNA | Mm is molar mass, not molarity |
| Concentration | M=n/V; M₁V₁=M₂V₂ | Solution liters; dilution without reaction or loss |
| Ideal gas | PV=nRT | Kelvin and absolute pressure; R matched to units |
| Heating | q=mcΔT; qphase=mL | One phase versus phase change |
| Reaction heat | qreaction≈−qsurroundings | Include apparatus/loss terms when needed |
| Free energy | ΔG=ΔH−TΔS | Kelvin and matching energy units; not reaction rate |
| Equilibrium | Q, K=products/reactants with powers | Omit pure phases in the school approximation |
| Acidity | pH≈−log[H₃O⁺] | Concentration approximation; neutral near 7 at 25°C |
| Buffer | pH≈pKa+log([A⁻]/[HA]) | Both conjugate species appreciable |
| Cell potential | E°cell=E°cathode−E°anode | Both table values are reduction potentials |
| Radioactive parent | N=N₀(½)^(t/thalf) | Closed parent accounting; statistical model |
Constants and unit conversions
| Value | Meaning / condition |
|---|---|
| NA=6.022×10²³ mol⁻¹ | Avogadro constant, rounded for school calculations |
| h=6.626×10⁻³⁴ J·s | Planck constant, rounded |
| c=3.00×10⁸ m/s | Vacuum light speed, rounded |
| e=1.602×10⁻¹⁹ C | Elementary charge magnitude; 1 eV=1.602×10⁻¹⁹ J |
| g=9.8 m/s² | Typical near-surface Earth approximation; use a supplied local value if given |
| R=8.314 J/(mol·K) | Use SI pressure Pa and volume m³ |
| R=0.0821 L·atm/(mol·K) | Use atmosphere pressure and liter volume |
| F≈96485 C/mol electrons | Faraday constant |
| 1 u·c²≈931.5 MeV | Mass-energy conversion for consistent nuclear mass accounting |
| T(K)=T(°C)+273.15 | Use 273 only when a question specifies that rounded convention |
| 1 L=1000 mL; 1 mL=1 cm³ | Volume conversions |
| 1 kWh=3.60×10⁶ J | Energy conversion |
| cwater≈4.18 J/(g·°C) | Approximate liquid-water specific heat in ordinary conditions |
| Lf,water≈334 J/g; Lv,water≈2260 J/g | Water fusion and vaporization near ordinary-pressure transition conditions |
Chemistry composition reference
Use these rounded atomic masses unless a problem supplies different values. Formula mass adds each atom’s contribution; isotopic mass and mass number are different quantities.
| Element / ion | Atomic mass or charge |
|---|---|
| H | 1.008 g/mol |
| C | 12.01 g/mol |
| N | 14.01 g/mol |
| O | 16.00 g/mol |
| Na | 22.99 g/mol |
| Mg | 24.31 g/mol |
| Al | 26.98 g/mol |
| P | 30.97 g/mol |
| S | 32.06 g/mol |
| Cl | 35.45 g/mol |
| K | 39.10 g/mol |
| Ca | 40.08 g/mol |
| Fe | 55.85 g/mol |
| Cu | 63.55 g/mol |
| Zn | 65.38 g/mol |
| Ag | 107.87 g/mol |
| NH₄⁺ / OH⁻ / NO₃⁻ | Ammonium +1; hydroxide −1; nitrate −1 |
| CO₃²⁻ / SO₄²⁻ / PO₄³⁻ | Carbonate −2; sulfate −2; phosphate −3 |
Midcourse checkpoint
Use relevant items as a diagnostic during the allocated chapter reviews and consolidation before the midterm. This guide question bank is not an additional timed examination on top of the scheduled midterm.
Use after the Grade 11 Solutions & Dissolved Particles chapter. Allow 60–90 minutes, calculator and the reference relationships, but keep solutions closed. Each task has three marking criteria; award up to 18 points. Revisit the named topic for each missing relationship or incorrect explanation before proceeding.
Question 1
An element has isotopes at 20 u (90%) and 22 u (10%). Find average atomic mass and distinguish it from mass number.
Worked solution and marking guidance
20(0.9)+22(0.1)=20.2.
20.2 u is a weighted average; mass number is an integer nucleon count for one isotope.
- 1 point: select a valid relationship, mechanism, or model.
- 1 point: show correct calculation or evidence-based reasoning.
- 1 point: give a correct conclusion with units and stated conditions.
Question 2
Write calcium nitrate and count oxygen atoms in three formula units.
Worked solution and marking guidance
Ca²⁺ requires two NO₃⁻; each Ca(NO₃)₂ has six O atoms.
18 O atoms in 3Ca(NO₃)₂.
- 1 point: select a valid relationship, mechanism, or model.
- 1 point: show correct calculation or evidence-based reasoning.
- 1 point: give a correct conclusion with units and stated conditions.
Question 3
Balance Al+O₂→Al₂O₃ and predict product from 4 mol Al with excess oxygen.
Worked solution and marking guidance
4Al+3O₂→2Al₂O₃; apply the 2/4 product ratio.
2 mol Al₂O₃.
- 1 point: select a valid relationship, mechanism, or model.
- 1 point: show correct calculation or evidence-based reasoning.
- 1 point: give a correct conclusion with units and stated conditions.
Question 4
N₂+3H₂→2NH₃ starts with 2 mol N₂ and 3 mol H₂. Actual product is 1.6 mol. Find theoretical yield and percent yield.
Worked solution and marking guidance
H₂ supports 2 mol NH₃; N₂ supports 4. Divide actual by theoretical.
H₂ limits; theoretical yield 2 mol; percent yield 80%.
- 1 point: select a valid relationship, mechanism, or model.
- 1 point: show correct calculation or evidence-based reasoning.
- 1 point: give a correct conclusion with units and stated conditions.
Question 5
Find volume of 1 mol ideal gas at 300 K and 1 atm using R=0.0821 L·atm/(mol·K). Why not automatically use 22.4 L?
Worked solution and marking guidance
V=nRT/P=24.63 L.
About 24.6 L; 22.4 L applies near 273 K and 1 atm.
- 1 point: select a valid relationship, mechanism, or model.
- 1 point: show correct calculation or evidence-based reasoning.
- 1 point: give a correct conclusion with units and stated conditions.
Question 6
A 0.50 mol sample reaches final volume 2.0 L, then is diluted to 4.0 L. Find both molarities.
Worked solution and marking guidance
Use M=n/V with unchanged solute amount if no loss or reaction.
0.25 M initially and 0.125 M after dilution.
- 1 point: select a valid relationship, mechanism, or model.
- 1 point: show correct calculation or evidence-based reasoning.
- 1 point: give a correct conclusion with units and stated conditions.
Cumulative course assessment
This 24-task guide bank is optional supplemental practice, not an additional required timed paper in the 180-session route. Select relevant tasks during consolidation or chapter review. A complete separate attempt requires extra/redistributed time; the scheduled midterm, sample and final have their own full papers and keys.
This assessment has 24 tasks, two for every chapter. Allow two sessions of 60–90 minutes. Use a calculator and reference relationships; keep answers closed until finished. This authored assessment is a course study check, not an official Regents examination.
Award up to three points per task using the worked criteria, for 72 total. A parent reviews written reasoning: a correct number alone can receive the conclusion point but not automatically all method points. Accept equivalent valid methods and a propagated arithmetic error with otherwise sound reasoning.
After marking, group errors by topic, redo one unfamiliar question for each gap, and explain a revised solution without notes. A suggested local target is at least 80% with no unresolved misconception in any chapter; this is teaching guidance, not a validated cut score. Pair the result with investigation notebooks and a capstone discussion.
Question 1
A 50.0 g solid displaces 20.0 mL water. Find density and describe an accuracy check.
Worked solution and marking guidance
ρ=m/V=50.0/20.0. Check a calibrated balance or independent volume reference.
2.50 g/mL. Repeated readings test precision; reference comparisons address accuracy.
- 1 point: select a valid relationship, mechanism, or model.
- 1 point: show correct calculation or evidence-based reasoning.
- 1 point: give a correct conclusion with units and stated conditions.
Question 2
Separate salt and sand while preserving both solids. Explain why filtration alone is insufficient.
Worked solution and marking guidance
Dissolve salt in water, filter and dry sand, then recover salt by safe evaporation.
Filtration removes sand particles; dissolved salt passes through with water.
- 1 point: select a valid relationship, mechanism, or model.
- 1 point: show correct calculation or evidence-based reasoning.
- 1 point: give a correct conclusion with units and stated conditions.
Question 3
Isotopes at 35 u and 37 u occur in 75% and 25% abundance. Find average mass.
Worked solution and marking guidance
35(0.75)+37(0.25).
35.5 u.
- 1 point: select a valid relationship, mechanism, or model.
- 1 point: show correct calculation or evidence-based reasoning.
- 1 point: give a correct conclusion with units and stated conditions.
Question 4
Compare 400 nm and 800 nm photon energies and explain atomic line spectra.
Worked solution and marking guidance
E=hc/λ; halving wavelength doubles energy. Allowed atomic level differences select photon frequencies.
The 400 nm photon has twice the energy; lines reflect discrete allowed transitions.
- 1 point: select a valid relationship, mechanism, or model.
- 1 point: show correct calculation or evidence-based reasoning.
- 1 point: give a correct conclusion with units and stated conditions.
Question 5
Write aluminum nitrate and count oxygen atoms in two formula units.
Worked solution and marking guidance
Al³⁺ balances three NO₃⁻; 2×3×3 oxygen atoms.
Al(NO₃)₃; 18 O atoms.
- 1 point: select a valid relationship, mechanism, or model.
- 1 point: show correct calculation or evidence-based reasoning.
- 1 point: give a correct conclusion with units and stated conditions.
Question 6
Explain why CO₂ is nonpolar while water is polar.
Worked solution and marking guidance
Use bond polarity and molecular geometry; compare vector dipole sums.
CO₂ is linear with cancelling dipoles; bent water has a nonzero molecular dipole.
- 1 point: select a valid relationship, mechanism, or model.
- 1 point: show correct calculation or evidence-based reasoning.
- 1 point: give a correct conclusion with units and stated conditions.
Question 7
Find an empirical formula from 24 g C and 8 g H using C=12 and H=1 g/mol.
Worked solution and marking guidance
Moles: C=2, H=8; divide both by 2.
CH₄. Composition alone does not establish every structural detail.
- 1 point: select a valid relationship, mechanism, or model.
- 1 point: show correct calculation or evidence-based reasoning.
- 1 point: give a correct conclusion with units and stated conditions.
Question 8
Write the net ionic equation when aqueous silver nitrate and sodium chloride produce solid AgCl.
Worked solution and marking guidance
Split aqueous strong electrolytes and cancel Na⁺ and NO₃⁻; check charge.
Ag⁺(aq)+Cl⁻(aq)→AgCl(s).
- 1 point: select a valid relationship, mechanism, or model.
- 1 point: show correct calculation or evidence-based reasoning.
- 1 point: give a correct conclusion with units and stated conditions.
Question 9
N₂+3H₂→2NH₃ begins with 1 mol N₂ and 2 mol H₂. Find limiting reactant and maximum product.
Worked solution and marking guidance
N₂ supports 2 mol product; H₂ supports 2×2/3 mol. Choose the smaller.
H₂ limits; maximum 4/3 mol NH₃.
- 1 point: select a valid relationship, mechanism, or model.
- 1 point: show correct calculation or evidence-based reasoning.
- 1 point: give a correct conclusion with units and stated conditions.
Question 10
What volume of 0.10 M NaOH neutralizes 25 mL of 0.20 M HCl in a supplied-data problem?
Worked solution and marking guidance
Acid amount=0.025×0.20=0.005 mol. The 1:1 ratio gives V=0.005/0.10 L.
50 mL.
- 1 point: select a valid relationship, mechanism, or model.
- 1 point: show correct calculation or evidence-based reasoning.
- 1 point: give a correct conclusion with units and stated conditions.
Question 11
Find volume of 1 mol ideal gas at 2 atm and 300 K with R=0.0821 L·atm/(mol·K).
Worked solution and marking guidance
V=nRT/P=24.63/2.
12.315 L, about 12.3 L.
- 1 point: select a valid relationship, mechanism, or model.
- 1 point: show correct calculation or evidence-based reasoning.
- 1 point: give a correct conclusion with units and stated conditions.
Question 12
Melt 10 g ice at 0°C and warm the liquid to 10°C. Use Lf=334 J/g and c=4.18 J/(g·°C).
Worked solution and marking guidance
Melting needs 3340 J; warming needs 418 J; add them.
3758 J. Phase change still absorbs energy during a temperature plateau.
- 1 point: select a valid relationship, mechanism, or model.
- 1 point: show correct calculation or evidence-based reasoning.
- 1 point: give a correct conclusion with units and stated conditions.
Question 13
Find molality for 0.20 mol sugar in 0.50 kg water and ideal freezing depression with i=1, Kf=1.86.
Worked solution and marking guidance
b=0.20/0.50=0.40; ΔTf=iKfb.
0.40 mol/kg and 0.744°C depression.
- 1 point: select a valid relationship, mechanism, or model.
- 1 point: show correct calculation or evidence-based reasoning.
- 1 point: give a correct conclusion with units and stated conditions.
Question 14
Why can salt water conduct while a sugar solution conducts poorly?
Worked solution and marking guidance
Identify which dissolved species can carry charge.
Dissolved salt supplies mobile ions; neutral sugar molecules do not supply comparable ion amounts.
- 1 point: select a valid relationship, mechanism, or model.
- 1 point: show correct calculation or evidence-based reasoning.
- 1 point: give a correct conclusion with units and stated conditions.
Question 15
A buffer has pKa=4.8 and equal conjugate acid/base amounts. Estimate pH and state a limitation.
Worked solution and marking guidance
pH≈pKa+log(1); both species must remain appreciable.
About 4.8; sufficiently large additions exhaust buffer capacity.
- 1 point: select a valid relationship, mechanism, or model.
- 1 point: show correct calculation or evidence-based reasoning.
- 1 point: give a correct conclusion with units and stated conditions.
Question 16
Estimate pH for 0.010 M strong monoprotic acid at 25°C. Compare hydronium with pH 4.
Worked solution and marking guidance
pH=−log(0.010)=2; factor=10^(4−2).
pH 2; 100 times the hydronium concentration in the introductory approximation.
- 1 point: select a valid relationship, mechanism, or model.
- 1 point: show correct calculation or evidence-based reasoning.
- 1 point: give a correct conclusion with units and stated conditions.
Question 17
A reaction warms 100 g water by 5°C. Use c=4.18 and neglect cup heat and losses. Find reaction heat.
Worked solution and marking guidance
Water gains 100×4.18×5=2090 J; reaction heat has opposite sign.
−2.09 kJ.
- 1 point: select a valid relationship, mechanism, or model.
- 1 point: show correct calculation or evidence-based reasoning.
- 1 point: give a correct conclusion with units and stated conditions.
Question 18
For ΔH=+20 kJ/mol, ΔS=+0.100 kJ/(mol·K), T=300 K, find ΔG. Does it determine rate?
Worked solution and marking guidance
ΔG=20−300(0.100); rate also depends on activation pathway.
−10 kJ/mol; favored does not mean fast.
- 1 point: select a valid relationship, mechanism, or model.
- 1 point: show correct calculation or evidence-based reasoning.
- 1 point: give a correct conclusion with units and stated conditions.
Question 19
For A⇌B, K=4 and current Q=0.5. Predict net direction and state the catalyst effect.
Worked solution and marking guidance
Q<K favors forward adjustment. A catalyst changes kinetics, not K at fixed temperature.
Net forward; equilibrium constant stays unchanged.
- 1 point: select a valid relationship, mechanism, or model.
- 1 point: show correct calculation or evidence-based reasoning.
- 1 point: give a correct conclusion with units and stated conditions.
Question 20
Concentration falls from 0.80 to 0.20 M in 30 s. Find average disappearance rate.
Worked solution and marking guidance
Use (0.80−0.20)/30 with a positive disappearance-magnitude convention.
0.020 M/s.
- 1 point: select a valid relationship, mechanism, or model.
- 1 point: show correct calculation or evidence-based reasoning.
- 1 point: give a correct conclusion with units and stated conditions.
Question 21
Cathode and anode reduction potentials are +0.34 and −0.76 V. Find standard cell voltage and external electron direction.
Worked solution and marking guidance
E°cell=0.34−(−0.76); oxidation supplies electrons at the anode.
1.10 V; electrons travel from anode to cathode through the wire.
- 1 point: select a valid relationship, mechanism, or model.
- 1 point: show correct calculation or evidence-based reasoning.
- 1 point: give a correct conclusion with units and stated conditions.
Question 22
A 96 g parent isotope has half-life 5 years. Find parent after 15 years and state alpha-decay count changes.
Worked solution and marking guidance
Three half-lives leave 96/8 g; alpha carries A=4 and Z=2.
12 g parent; daughter mass number decreases 4 and atomic number decreases 2.
- 1 point: select a valid relationship, mechanism, or model.
- 1 point: show correct calculation or evidence-based reasoning.
- 1 point: give a correct conclusion with units and stated conditions.
Question 23
Give the formula of a five-carbon acyclic alkane. Explain how ethanol and dimethyl ether can share a formula but differ in properties.
Worked solution and marking guidance
CnH₂n+₂ gives C₅H₁₂; different connectivity changes functional groups and intermolecular interactions.
C₅H₁₂; ethanol has an O–H donor while the ether does not.
- 1 point: select a valid relationship, mechanism, or model.
- 1 point: show correct calculation or evidence-based reasoning.
- 1 point: give a correct conclusion with units and stated conditions.
Question 24
Reusable production impact is 120 units plus 1/use; disposable is 5/use. Find break-even and two model limits.
Worked solution and marking guidance
Solve 120+n=5n; assess lifespan and washing/end-of-life boundary.
Equal at 30 uses; reusable lower afterward under the assumptions.
- 1 point: select a valid relationship, mechanism, or model.
- 1 point: show correct calculation or evidence-based reasoning.
- 1 point: give a correct conclusion with units and stated conditions.
Investigation record and discussion rubric
- Record date, minutes actually spent, question, prediction, materials, safety review, and setup diagram.
- Identify changed and measured variables, comparison, independent repetitions, and instrument resolution; for supplied data, identify the dataset and model boundary.
- Keep raw values, labels, units, graphs, calculations, and observations separate from interpretation.
- Write claim, evidence, mechanism, limitations, alternative explanations, and a next test.
- For each of four criteria—design, data, reasoning, evaluation—use 0 (missing), 1 (partial), or 2 (clear and accurate), for a maximum of 8. Discuss omissions before recording a final mark.
- Provided-data analysis is valid study work, but does not establish that an experiment was performed or that supervised laboratory requirements were met.
When you get stuck
First locate the error: vocabulary, representation, model choice, algebra, units, or arithmetic. Read the relevant paragraph again and reproduce one example with the answer hidden. Then change one number or condition and explain what should change before calculating.
For laboratory data that disagree with a model, inspect measurement method and model assumptions instead of altering results to match the example. If the guide’s supplied data are used, label that clearly. Ask an adult to listen to your explanation; they can use the worked criteria to identify the next topic to revisit.
Use the chapter review for practice and the chapter quiz for an independent attempt. Repeated exposure to the same fixed questions can inflate a score, so use the cumulative unfamiliar tasks, notebook evidence, and changed-condition explanations to check transfer.
Two core sessions, with selected third sessions
Plan separate investigation blocks for method design, measurements or explicitly supplied-data analysis, graphing, and scientific argument. Chapter review and quizzes belong after the units. Use the midterm, sample paper, and final at their assigned course points, with separate correction time. Add or redistribute sessions based on independent understanding rather than assuming equal difficulty for all 46 units.
| Session | Study and evidence to retain |
|---|---|
| Core 1 | Opening phenomenon, core explanation and Parts 1–2; vocabulary, labeled first model, visual questions and a first worked attempt. |
| Core 2 | Parts 3–4, whole-unit application, varied worked/independent practice, exit check and explained correction. |
| Selected third | The weekly plan assigns a third session to 18 demanding topics for calculations, modeling and changed independent transfer. Extend other topics when feedback requires it. |
Using figures, calculated curves and source templates
Read a figure with its explaining paragraph, units, caption and question. Models show selected relationships; a molecule, ion, formula unit, probability distribution and measured record are not interchangeable pictures. A calculated curve is labeled as a model rather than evidence personally collected.
Four public OpenSciEd middle-school source excerpts are credited foundation prompts. Empty learner-model circles are intentionally unfinished and are paired with complete local chemistry explanations and original advanced figures. This is independent teaching, not a reproduction of OpenSciEd high-school teacher editions or an endorsement.
Optional WeduLab explorations
Selected units now link to independently operated WeduLab visual models. Open the optional guided lab after reading the relevant explanation: predict first, change one condition, record the model settings, and explain the result. The original question and supplied record remain usable here without visiting the other site.
Use one of these 15–25 minute explorations in place of comparable practice, or as additional study. The existing 180-session timetable and course assessments are unchanged. A simulation supports model-based reasoning; it does not by itself demonstrate practical laboratory skill or satisfy a school laboratory requirement.
Links were reviewed on 17 October 2026. We have not copied WeduLab code, graphics or text, and have not verified an explicit redistribution or embedding license in the pages reviewed. The activities open as external links rather than loading third-party scripts or embedded labs into this course. Availability, language options and interface behavior can change.
Curriculum references
The the published district directory informs course scope and school laboratory expectations. Our grade labels, chapter/unit split, pacing, and assessments are independently authored. Standards codes are topic connections; a full performance expectation requires more evidence than a matching topic name.
The local high school 2026–27 science directory · New York State science learning standards
Reviewed for topic gaps, calculation conditions, scientific overstatements, and self-study support on 2026-10-10. Classroom timing and a full performance-standard audit remain separate validation work.
Independently authored homeschool study materials. The grade placement, chapter sequence, pacing, and assessments are our teaching design. They have not been approved by the district; supervised laboratory eligibility and full Regents performance-standard validation are separate.