Hydrogen Pop Test: Approving a Lab with Limited Safety Controls
Mr. L plans a 45-minute lab for 32 students in a room with eight stations. Each station will add a 3.0 cm strip of magnesium ribbon to 10 mL of 6.0 M HCl in a 50 mL graduated cylinder, collect hydrogen in a balloon, and then bring the balloon near a Bunsen burner for a “pop” test. Only 12 splash goggles are available, and the eyewash/safety shower is down the hall, about 25 seconds away. The chemical hygiene plan lists 6.0 M HCl as corrosive and hydrogen as flammable. SDSs are kept in the main office. One student has long hair and wears a loose hoodie; another station is already using a Bunsen burner for a flame test. Mr. L asks whether he should approve the activity as written, modify it, or postpone it. He wants a decision that is defensible, not just “be careful.”
1. Identify at least three specific safety deficiencies in the plan and give a concrete correction for each.
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First, PPE is inadequate: only 12 goggles for 32 students means many students lack splash protection while handling 6.0 M HCl; the activity should not start until every student has goggles and, given the corrosive, a lab apron or coat. Second, the eyewash/safety shower is about 25 seconds away; ANSI Z358.1 calls for emergency eyewash within 10 seconds of unobstructed travel, so the room is not suitable for corrosive handling unless the equipment is relocated or the activity is moved. Third, open flames are present while hydrogen is being generated and tested; the balloon pop should be a controlled demonstration away from other burners, using a small volume and an igniter on a long handle, or replaced with a safer gas test. Fourth, loose hair and a hoodie near a burner are ignition/entanglement hazards; hair must be tied back and loose clothing secured. SDS access should also be immediate, not in the office.
2. Using the hierarchy of controls, decide whether to approve, modify, or postpone the activity. Justify your decision with the hazards you identified.
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The activity should be modified substantially or postponed, not approved as written. The highest-priority control is elimination/substitution: replace the open-flame pop test with a safer demonstration-for example, collect a small known volume of hydrogen and ignite it behind a blast shield with a long-handled igniter, or show a video/teacher-only demonstration. Engineering controls come next: use a functioning fume hood or local exhaust for HCl, and ensure an eyewash within 10 seconds. Administrative controls include reducing the scale (less 6.0 M HCl, smaller Mg strip), limiting the number of students handling acid at once, and requiring a pre-lab safety check. PPE-goggles, aprons, and secured hair/clothing-is the last line of defense, not the first. If the eyewash cannot be made compliant or the open flames cannot be separated, the lab should be postponed.
3. A student refuses to wear goggles because they are uncomfortable. How should Mr. L respond, and what should happen before the class proceeds?
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Mr. L should stop the activity for that student and explain that goggles are a non-negotiable condition for working with corrosive liquids, not a personal preference. He should offer a comfortable, properly fitting pair and allow the student to adjust the strap; if the student still refuses, the student cannot participate in the wet lab and should be given an alternative assignment while the rest of the class proceeds only if all safety conditions are met. The teacher should document the refusal and contact the parent/guardian according to school policy. Before the class proceeds, he should verify that every student has goggles and aprons, that hair and loose clothing are secured, that the eyewash is accessible within 10 seconds, and that the hydrogen test is controlled. Safety is a precondition for the lab, not a concurrent activity.