Science Laboratory Safety, Techniques, and Data Analysis
This domain tests safe laboratory practice, correct use of equipment, separation and measurement techniques, and data analysis. Questions may ask you to choose PPE, interpret an SDS, select a technique, or evaluate error and graphing.
Core rules and concepts
- Wear goggles, gloves, and apron as required. Know emergency equipment: eyewash, safety shower, fire extinguisher, and spill kit. Never taste or directly smell chemicals.
- Read the SDS for hazards, handling, and waste. Label containers; never return unused chemicals to stock bottles.
- Add acid to water, not water to acid, to control heat. Heat test tubes at an angle, pointing away from people.
- Use a burette for precise titrant delivery, a volumetric flask for fixed-volume solutions, and a graduated cylinder for approximate volumes. Read the meniscus at eye level.
- For data analysis, distinguish random error from systematic error. Percent error = |measured − accepted| / accepted × 100%.
Worked example
A student measures a product mass as 9.8 g; the accepted value is 10.0 g. Percent error = |9.8 − 10.0| / 10.0 × 100% = 2%. If the student’s repeated values are all close to 9.8 g but far from 10.0 g, the set is precise but has a systematic bias.
Traps that cost marks
Do not add water to concentrated acid. Do not read a meniscus from above or below eye level. Do not call a precise measurement accurate. Do not ignore units or significant figures when reporting. Do not discard an outlier without justification; investigate it first.