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Every rule on your school lab wall sounds fussy until you know the accident behind it. The ten rules below come from the School Chemistry Laboratory Safety Guide, published in October 2006 by the US Consumer Product Safety Commission and NIOSH for high school chemistry teachers. Indian school labs use many of the same acids, burners and glassware, so the reasons apply to your CBSE or state board practicals too.
Why do chemistry labs have so many safety rules?
The NIOSH guide opens its section for students with this line: “Life threatening injuries can happen in the laboratory.” The rules guard against a handful of hazards: splashes, fires, chemicals swallowed or breathed in, and mix-ups.
In January 2006, a 15-year-old student in Ohio “was burned over 40 per cent of her body” when her teacher poured methanol onto an open flame during a chemistry demonstration, according to the US Chemical Safety Board. In September 2014 in Denver, methanol added from a four-litre bulk container during a demonstration caused a 12-foot flash fire that burned four students, one seriously, the Chemical Safety Board reported.
What are the 10 lab safety rules and the reasons for each?
Each rule is taken from the NIOSH student checklist, followed by the accident it prevents.
Wear chemical splash goggles the whole time. Prevents: acid or alkali splashing into your eyes while you pour, heat or clean up.
Add concentrated acid to water slowly, never water to acid. Prevents: a boil-over. The University of Illinois Division of Research Safety warns that adding water to concentrated acid “may cause violent boiling of the solution and splashing.”
Never fill a pipette by mouth; use a pipette filler. Prevents: a mouthful of acid or a toxic solution when the liquid rises faster than you expect.
Keep flammable solvents away from flames, and heat them in a water bath. Prevents: flash fires like the methanol accidents above.
Never point the open end of a test tube at yourself or anyone else. Prevents: hot liquid spurting into a face if the contents boil suddenly.
Never touch, taste or smell a reagent. Prevents: poisoning and burns to your nose and throat. The guide also says never hold a container under your nose and breathe in the vapour.
No food, drink or cosmetics in the lab, and never eat or drink from lab glassware. Prevents: swallowing traces of chemicals from benches and hands.
Tie back long hair, secure loose sleeves and dupattas, and wear shoes that cover the whole foot. Prevents: hair or cloth catching a burner flame, and spills landing on bare feet.
Check the label before you use a chemical, and label anything you transfer. Prevents: using the wrong chemical. A label should give the contents, concentration, hazard, date and your initials.
Take only what you need, and never pour the excess back into the stock bottle. Prevents: contaminating the bottle the whole class uses next.
Two more lines from the same checklist are worth learning by heart: “Hot glassware looks just like cold glassware,” and “Never attempt to catch a falling object.”
What should you do in the first minute if something goes wrong?
Tell your teacher at once. The NIOSH guide says to “Immediately report any spills, accidents, or injuries to a teacher,” and its emergency appendix lists these first steps:
Chemical in the eye: flush with water straight away while holding the eye open, take out contact lenses and keep rinsing, then get medical attention.
Acid or alkali on the skin: remove soaked clothing, flush with plenty of cold water for at least 5 minutes, and get treatment from medical staff.
The University of Illinois acid safety guide asks for longer: at least 15 minutes at the eyewash, and 15 minutes of rinsing for acid on the skin. Always follow your school's emergency plan, and find the eyewash, fire blanket and exits before you start work.
How can you prepare for a practical so the rules feel automatic?
Use this routine for every practical:
The night before, read the procedure and underline every chemical, flame and heating step.
Next to each underlined step, write the rule that applies, such as “acid into water” beside a dilution.
At the bench: goggles on, hair tied, bag off the bench, eyewash and fire blanket located.
Before you leave: burner and taps off, waste in the labelled container (the guide says never down the sink), hands washed.
The same thinking earns marks in your record. Our guide on how to write precautions and sources of error in practicals shows the format, and Class 9 and 10 science practicals covers drawing and recording.
If the chemistry behind a rule is the part you don't understand, such as why diluting sulphuric acid releases so much heat, the Fermi Concept Library has a lesson for every concept in chemistry. Read the idea at home before you meet it at the bench.
Copy the ten rules into the first page of your practical file, and read them aloud with your lab partner before anyone lights a burner.
