Chemistry practicals are where theory meets the real world — and where real risks live. Over a career spanning laboratories at three universities and hundreds of tutoring sessions on practical technique, I have seen the same safety mistakes made by otherwise excellent students, repeatedly. This guide covers what the syllabus requires, what examiners look for, and what actually keeps you and your colleagues safe.
There is also an interactive pre-lab safety quiz and a full lab session checklist below — tools you can use before every practical to make sure nothing important is missed.
"In a laboratory, the most dangerous person is not the one who doesn't know something. It is the one who doesn't know they don't know it — and acts on that false confidence."
— Fahad Rafiq, Chemistry & Biology TutorEvery serious lab accident I am aware of shares a common feature: the person involved did not know something about their environment that they needed to know. The chemical they assumed was dilute was concentrated. The fire exit they assumed was behind them was actually to their left. The eye wash station they needed in the first thirty seconds took them two minutes to find.
Before your first session in any laboratory, locate and physically walk to each of the following: the fire extinguisher, the fire exit, the emergency shower, the eye wash station, and the first aid kit. Do not point at them on a diagram. Walk to them. In an emergency, muscle memory is faster than thought.
Safety questions appear in every CIE A Level Chemistry practical paper and in Edexcel's practical endorsement assessments. Examiners expect you to identify specific hazards for named chemicals (not just "it's dangerous"), explain the correct PPE for each scenario, and describe the correct emergency response. Generic answers like "wear gloves" earn zero marks. "Wear nitrile gloves resistant to [specific chemical] to prevent skin absorption" earns marks.
Read the Material Safety Data Sheet (MSDS) for every chemical you will use before the practical begins. These are not bureaucratic documents — they contain the exact information examiners expect you to demonstrate: the specific hazard class, the correct PPE, and the emergency procedure for exposure. Schools and colleges are required to have these available. Ask your teacher to show you where they are kept.
Personal protective equipment is not a costume. A lab coat with the sleeves rolled up does not protect your forearms from splashes. Safety goggles worn on your forehead do not protect your eyes. Gloves that are too large for your hands reduce your tactile sensitivity to the point where you are more likely to drop something than if you were wearing none at all.
Never pipette chemicals by mouth. This practice was common in teaching labs decades ago and is completely prohibited now. Use a pipette filler or bulb. The concentrations of acids, bases, and organic reagents used in A Level practicals are sufficient to cause serious internal injury if ingested even in small quantities.
A Level Chemistry involves a wide range of chemical hazard classes, and the correct handling procedure differs significantly between them. The most common student error — both in the lab and in exam answers — is treating all hazardous chemicals identically. "Handle carefully and wear gloves" is not a meaningful safety protocol.
Never dispose of chemicals down the sink unless your supervisor has explicitly confirmed this is appropriate for the specific substance. Many organic solvents are insoluble in water and will float on it; some react violently with water; others are environmentally toxic at concentrations that your school's drain cannot handle. There are designated waste containers for organic waste, halogenated waste, and aqueous waste — use the correct one and label what you put in it.
Before you enter any lab, you should be able to answer these questions correctly. Try the quiz — the explanations are worth reading even if you get the answer right.
Run your finger along every piece of glassware before use and inspect under the bench light. A crack that is invisible in ambient light will fail under thermal stress. A chip on the rim of a beaker will cut your hand when you pour from it. Replacing a cracked flask takes thirty seconds. Dealing with a chemical burn from broken glass takes considerably longer.
For Bunsen burners: check the gas hose for cracks, ensure the collar is functional, and light the burner by striking the lighter first and then opening the gas — never the other way around. The characteristic yellow safety flame should be used when not actively heating; never leave a blue flame unattended.
Want to work through practical exam questions and mark scheme technique with a tutor before your assessment? Your first session is free.
Book a Free Trial →This is one of the most mark-costly mistakes in A Level practical assessments, and it is entirely avoidable. Students who understand the chemistry often write what the reaction should produce — the theoretical outcome — rather than what they actually saw happen. Examiners are explicit on this point: observation marks require observation language.
Document measurements with full units and appropriate significant figures. If your burette reads 24.35 cm³, write 24.35 cm³ — not 24, not 24.4, not "about 24." Significant figures in practical work communicate the precision of your measurement, and examiners are trained to spot when they are arbitrarily rounded.
If your observations differ from the expected result, record what you actually saw and note the discrepancy. Investigating unexpected results — suggesting possible sources of error, proposing variables that may have affected the outcome — earns evaluation marks. Morphing your real results to match the textbook earns nothing and undermines the entire point of practical science.
Every lab emergency procedure is designed to be followed calmly under pressure. Knowing the procedure in advance — not just knowing that a procedure exists — is what allows you to follow it calmly. The difference between knowing "use the eyewash if something gets in your eye" and knowing exactly where the eyewash is, how to open it with one hand while keeping the other over your eye, and that you need to hold your eye open and flush for at least fifteen minutes is enormous in the moment it matters.
Students frequently do not report small incidents — a minor splash, a brief skin contact with a dilute solution — because they feel embarrassed or do not want to cause disruption. Report them anyway. Some chemical exposures have delayed effects that only become apparent hours later. Your supervisor cannot help you if they do not know what happened. The purpose of incident reporting in a teaching lab is not punishment — it is protection.
One of the most underused applications of tutoring is practical preparation. Students typically use sessions to work through theory questions — and then walk into their practical exam having never discussed what they are about to do or what they should expect to observe. This is a mistake that costs marks in every practical paper.
Before any significant practical, spend part of a tutoring session walking through the experiment conceptually: what is the underlying chemistry, what do you expect to observe at each step and why, what would an unexpected result suggest, and what safety precautions apply to the specific chemicals involved. This kind of preparation takes twenty minutes and transforms the experience from one of anxious improvisation to informed execution.
Virtual lab simulations — PhET, Chemguide's interactive resources, and exam board virtual practicals — are genuinely useful for pre-lab preparation. They let you run through the procedure, make the common errors in a safe environment, and develop a mental model of what you should be seeing before you handle real reagents. I recommend using them before any practical you have not done before, and asking your tutor to walk through the simulation with you so that questions arise in a context where they can be answered immediately.
Use this before every practical session. Tick each item off as you confirm it. Items marked Critical are non-negotiable — do not begin the practical until they are confirmed.
Lab safety is not just a set of rules to comply with — it is a culture of mutual responsibility. When you see a colleague working without goggles, say something. When you notice a cracked flask on a shelf, remove it. When spills are cleaned up promptly, everyone benefits. The laboratories where accidents are rare are not the ones with the strictest rules — they are the ones where every person in the room takes responsibility for the whole room. Build that habit now and it will serve you in every laboratory you work in for the rest of your scientific career.
We cover practical technique, safety protocols, observation language, and past practical exam papers — all in your free first session. No card required.
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