Scientific Inquiry and the Processes of Chemistry
The Scientific Inquiry and the Processes of Chemistry domain tests how chemists frame questions, design investigations, handle measurement, and communicate evidence. Expect items on experimental variables, significant figures, unit analysis, error, graphing, laboratory safety, and the role of models in chemistry.
Core rules and concepts
- Scientific explanations are tentative and evidence-based; models are revised when data conflict.
- A controlled experiment changes one independent variable while holding others constant; the dependent variable is measured.
- Accuracy is closeness to true value; precision is reproducibility. Random error scatters; systematic error biases.
- Significant figures: all nonzero digits count; captive zeros count; leading zeros do not; trailing zeros count only with a decimal point.
- Use dimensional analysis so units cancel and the result has the right unit and magnitude.
- Graphs should label axes with units; slope often carries physical meaning; R² describes fit, not correctness.
Worked example
A student finds the mass of a 25.00 mL sample is 24.63 g. Density = 24.63 g / 25.00 mL = 0.9852 g/mL. The volume has four significant figures and the mass has four, so the quotient is reported to four. If the accepted density is 0.9970 g/mL, percent error = |0.9852 − 0.9970| / 0.9970 × 100% = 1.18%. The small negative deviation suggests a systematic error such as a mis-calibrated pipet, not random scatter.
Traps that cost marks
- Rounding at intermediate steps instead of carrying extra digits.
- Treating precision and accuracy as synonyms.
- Forgetting that trailing zeros need a decimal point to be significant.
- Reversing independent and dependent variables.
- Using a graph’s R² as proof that the method is valid.