Laboratory Work, Safety and Laboratory Techniques
What you must understand
Know safety rules: goggles, lab coat, no eating, no open flames near flammables, never pipette by mouth, add acid to water (not water to acid), read labels and hazard symbols. Know first aid basics: rinse spills with water, neutralise acid spills with sodium bicarbonate, report accidents.
Equipment and techniques: measuring volumes with graduated cylinders, pipettes, burettes; weighing with analytical balances; heating with Bunsen burner; filtration, decantation, crystallisation, distillation, extraction, chromatography. Understand separation methods and when to use each.
Handling: correct use of test tubes, clamps, stands; heating test tubes at an angle; pointing openings away from people. Waste disposal and recycling. Record observations accurately, distinguish observation from inference, and report data with units and correct significant figures.
Traps
Never add water to concentrated acid - it splashes. Don't use a Bunsen burner flame for flammable solvents. Don't confuse filtration (insoluble solid from liquid) with distillation (separation by boiling point). Significant figures and units in reporting matter.
Rule of thumb
Always add the more concentrated reagent to the more dilute one slowly, with stirring - especially acid into water.
Worked example
Separating sand and salt: dissolve in water, filter to remove sand, then evaporate the filtrate to crystallise salt.