Storing reagents and disposing of lab waste
Decide where a reagent is stored, how it is labeled, and which waste stream each item leaves in, using the SDS and the container label.
- Finding a section in an SDS: Storage and disposal each have their own numbered SDS section, so the skill starts with knowing where to look.
- Telling one hazard class from another: Flammable, corrosive and biological hazards are stored and discarded differently, so naming the hazard comes before choosing the shelf or the bin.
Prerequisites are inferred: pending teacher review.
Re-learn the skill with worked practice and clear examples.
Sort real items into the right storage place and the right waste stream.
A group finishes a transformation lab. Which item leaves in the biological waste, to be bleached or autoclaved rather than put in the classroom bin?
Reviewed- A.The agar plate that grew bacterial colonies
- B.The paper towel used to dry clean hands
- C.The empty cardboard box the sterile tips arrived in
- D.The marker used to label the plates
Show the worked solution ▾
Answer: A. The agar plate that grew bacterial colonies
- Step 1: Ask what touched living cultures: Biological waste is defined by contact with the organisms, not by the material.
- Step 2: Follow the one that did: The plate grew colonies, so it leaves as biological waste and is decontaminated first.
Why it's right: The agar plate grew live bacterial colonies, so it is biological waste and must be bleached or autoclaved before disposal. The other three never contacted the culture.
- B: Drying clean hands means the towel touched no culture. It is ordinary trash.
- C: Packaging that never entered the working area and never held culture is ordinary recycling or trash.
- D: The marker wrote on the OUTSIDE of the plate lid and never contacted the growth surface.
Aligned to Handling, Preparation, Storage and Disposal · reading level ~grade 9
A bottle of 70 percent isopropyl alcohol is currently stored on the open shelf directly above a hot plate. What should change, and why?
Reviewed- A.Move it to the corrosives tray, because alcohol burns skin
- B.Move it to the flammables cabinet, because a heat source sits directly below a flammable liquid
- C.Move it to the refrigerator, because alcohol evaporates at room temperature
- D.Nothing, because 70 percent alcohol is mostly water
Show the worked solution ▾
Answer: B. Move it to the flammables cabinet, because a heat source sits directly below a flammable liquid
- Step 1: Name the hazard: Isopropyl alcohol at 70 percent is a flammable liquid, and its vapor is what ignites.
- Step 2: Name what is wrong with the location: A hot plate is an ignition source, and vapor collects above the bottle and below the shelf.
Why it's right: 70 percent isopropyl alcohol is flammable and a hot plate is an ignition source. Storing a flammable liquid directly above one is the specific arrangement its SDS storage section tells you to avoid, so it belongs in the flammables cabinet.
- A: Alcohol dries and irritates skin, but it is not classed as corrosive. The corrosives tray is for acids and bases, and putting a flammable there mixes incompatible classes.
- C: Refrigerating slows evaporation but does not address the hazard, and a standard refrigerator is itself an ignition source: the interior light and thermostat can spark.
- D: The remaining 30 percent water does not stop it burning. 70 percent isopropyl alcohol still ignites readily, which is why it carries a flammable label.
Aligned to Handling, Preparation, Storage and Disposal · reading level ~grade 9
Fill these in as you work through the lesson.
- SDS (the safety data sheet):
- Incompatible (must not be stored together):
- Waste stream (which container it leaves in):
- Secondary container (the tray that catches a spill):
Before you put a reagent away, read SDS section for storage; before you throw anything out, read section for disposal.
- Why are flammables kept in their own cabinet rather than on the shelf with everything else?
- What is the difference between something that goes in the regular trash and something that goes in a biohazard bag?
- A bottle has no label. What is the safest thing to do with it, and why is guessing the worst option?
A bottle of 70 percent isopropyl alcohol: SDS section 7 says store away from heat and ignition sources, so it belongs in the flammables cabinet, not beside the hot plate. Section 13 says do not pour it down the drain, so it leaves in the labeled solvent waste container.