IB Chem IA Guide-AI-powered Chemistry IA Guidance

Example

Transform “Effect of temperature on reaction rate” into: “How does temperature (15.0–45.0 °C, 5.0 °C steps) influence the rate constant k of the iodate–bisulfite reaction at constant ionic strength (μ ≈ 0.10 mol dm⁻³) measured by the iodine clock endpoint?” The scope is justified by: measurable time window (10–120 s), safe reagents, and available thermometer accuracy (±0.1 °C).

Scenario

Student describes interests (kinetics, green chemistry, food chemistry). The Guide narrows variables, defines a realistic range and step size, identifies a measurable dependent (initial rate or k from slope), and articulates controls (ionic strength, pH, total volume, mixing method). It flags feasibility (e.g., if temperature control is weak, recommend a water bath + calibrated thermometer; if time resolution is coarse, suggest larger volume or lower catalyst loading to slow the reaction). It also proposes an a priori data density plan (≥5 levels × 3 trials) and a quick power-style sanity check: will expected signal exceed instrument noise by at least ~10×?

Example

Vitamin C (ascorbic acid) in juice by DCPIP titration. The Guide drafts a ready-to-use raw-data table with units and estimated uncertainties: - Burette readings: 0.00–50.00 mL (±0.05 mL each reading) ⇒ V_titre uncertainty ≈ ±0.10 mL. - Pipette: 10.00 mL (±0.02 mL). - Standardization of DCPIP using pure ascorbic acid (mass on balance ±0.001 g). It outlines propagation: c(AA) = (c_DCPIP × V_titre / V_sample); relative uncertainty combines volumetric and standardization components; include random scatter (s/√n) in the final combined uncertainty. It specifies acceptance criteria (concordant titres within 0.10–0.15 mL) and a bias check via spike recovery (95–105%).

Scenario

Before any lab work, the Guide helps the student pre-build a data schema (clearly labeled trials, units, significant figures), choose appropriate ranges (avoid saturation in colorimetry; keep absorbance 0.1–1.0 A), and plan calibration (e.g., 6–8 standards evenly spanning the range). It recommends control strategies (rinse burette with titrant, discard first titre, constant swirl rate), safety notes (DCPIP staining, acid handling), and a written method that minimizes confounders (constant light path in cuvettes; rinse protocols; temperature stabilization). It also pre-computes expected magnitudes so students can catch impossible numbers during collection.

Example

Colorimetry of FeSCN²⁺: students generate a calibration curve A = εℓc, fit A vs. c with least squares, report slope (εℓ) with standard error, R², and a residual plot to check linearity. For an unknown, they propagate uncertainty from both the regression (slope SE) and the absorbance reading (±0.005 A). They flag an outlier standard with standardized residual > |2| and justify retain/remove with a chemical reason (e.g., improper mixing). For kinetics (H2O2 decomposition), they obtain initial rates from tangent slopes at t → 0 or by linear fit to early-time O₂ volume; they test a rate law via log–log plots: log(rate) vs. log[H2O2] (slope ≈ order).

Scenario

After collection, the Guide walks through: (1) cleaning data (units, sig figs, blanks), (2) choosing the right model (linear fit, polynomial only if physically justified; linearization like ln[P] vs. t for first-order), (3) calculating combined uncertainties (instrumental ⊕ random) and showing error bars, (4) diagnosing anomalies (residuals, leverage points), (5) interpreting chemistry (linking slope/intercept to ε, k, ΔH‡ if using Arrhenius), and (6) writing concise, criteria‑mapped conclusions and evaluations: effect size with uncertainty (k = 0.132 ± 0.006 s⁻¹), strength of evidence (does the uncertainty band support the claim?), limitations (e.g., temperature drift ±0.3 °C inflates rate), and targeted improvements (thermostatted bath; automated timing; ionic strength buffer). The Guide supplies sentence templates that remain student‑owned (e.g., “Our model explains __% of variance; residual pattern suggests __; chemically, this likely reflects __”).