IB Chemistry · first assessment 2025
Paper 1B: data & experimental skills
Paper 1B is where chemistry knowledge meets unfamiliar data and experimental work. The current guide gives SL 25 marks within a 1 h 30 min combined Paper 1, and HL 35 marks within a 2 h combined Paper 1. Calculators and the Chemistry data booklet are permitted.
Independent study resource. This page summarizes skills from the public Chemistry guide and uses original examples; it does not reproduce official examination questions.
Data handling
Read raw and processed tables; calculate mean, range, rates, percentages and ratios; use scientific notation and appropriate significant figures.
Uncertainty
Record ± ranges; express absolute, fractional and percentage uncertainty; propagate through +, −, × and ÷, with exponents at HL.
Graphs
Construct and interpret scatter, line and curve graphs; use best fit, gradients, intercepts, maxima/minima, areas, uncertainty bars, interpolation and extrapolation.
Experimental techniques
Understand the purpose of standard solutions, dilutions, titrations, calorimetry, chromatography, separation, electrochemical cells, colorimetry/spectrophotometry, recrystallization and melting-point work.
Evaluation
Identify patterns and outliers; distinguish random and systematic effects; discuss precision, accuracy, reliability and validity; propose specific improvements.
Chemical reasoning
Use stoichiometry, energetics, kinetics, equilibrium and structure concepts to interpret unfamiliar experimental contexts rather than memorizing one fixed practical.
High-value calculator set
Calibration curve
Fit a linear calibration curve, report slope, intercept and R², and calculate an unknown concentration from its response.
Open calculatorTitration stoichiometry
Calculate an unknown concentration at equivalence from the known concentration, titre volumes and balanced-equation coefficients.
Open calculatorCalorimetry
Calculate heat transferred and molar enthalpy from mass, specific heat capacity, temperature change and amount reacted.
Open calculatorReaction rate
Calculate an average rate from a change over time, or the common inverse-time rate proxy used in clock-style experiments.
Open calculatorPercentage uncertainty
Convert an absolute measurement uncertainty to percentage uncertainty and report a rounded x ± Δx result.
Open calculatorUncertainty propagation
Propagate school-lab uncertainties through addition, subtraction, multiplication and division; power propagation is clearly marked HL-only.
Open calculatorSignificant figures
Round a decimal or scientific-notation value to a chosen number of significant figures and explain which zeros carry meaning.
Open calculatorError & difference
Calculate percentage error against a reference, percentage difference between two measurements, or signed percentage change.
Open calculatorFormula map worth knowing how to use
| Area | Relationships | What the question may test |
|---|---|---|
| Amount & solutions | n=m/M; n=CV; C₁V₁=C₂V₂ | Stoichiometry, standard solutions, dilution, titration. |
| Gases | PV=nRT | Unit conversion, model assumptions, amount from P-V-T data. |
| Energetics | q=mcΔT; ΔH=−q/n; Hess relationships | Signs, system/surroundings, heat-loss evaluation. |
| Acids | pH=−log₁₀[H⁺]; Kw=[H⁺][OH⁻] | Logarithms, concentrations and at HL pOH/Kw relationships. |
| Kinetics | rate≈Δquantity/Δt; HL rate law & Arrhenius | Initial rates, order, graph gradients and temperature effects. |
| Equilibrium | K/Q expressions; HL ΔG°=−RT ln K | Construct/evaluate expressions and interpret equilibrium position. |
| Uncertainty | absolute, fractional, percentage; +/−/×/÷ propagation; powers HL | Processed values, reported precision and quality of evidence. |
A reliable way to attack a Paper 1B data question
- Identify what was directly measured, its unit and stated uncertainty.
- Separate raw data from quantities calculated from it.
- Write the chemical relationship before substituting numbers.
- Inspect the graph: axes, units, trend, intercept, outliers and whether interpolation or extrapolation is being used.
- Carry uncertainty and significant figures only as far as justified by the data.
- For evaluation, connect a specific limitation to its likely effect and to a targeted improvement.
Try 18 original Paper 1B tasks Experimental skills checklist