Like most high school chemistry teachers, you have probably inherited someone else’s laboratory and prep room. This can be a gift, but in many ways it is also a curse—especially for the new and/or overwhelmed teacher. You may have tried to clean up and organize your lab, but perhaps your missions have ended like many of my attempts: What does that label say? Wait, should I even have that compound in my room? How do I get rid of this solvent? Hold on … should my chemicals be in alphabetical order? A few months ago, this was the situation I was in. However, I have learned that I can get the lab clean and organized, even with a full plate of teaching, planning, and grading. I just have to tackle the task in many short sessions.

The goal of this article is to break down the most important tasks into efficient, doable steps that all of us can handle. If you can spare just a few minutes in a day, you can get your lab whipped into shape!

Where to begin

The first step is to determine what you actually need in your prep room. One of the first things I realized was that I didn’t use, or even recognize, many of the chemicals I had on hand. Start by making a list of the labs you generally teach in each course, and then identify the chemicals (name and formula) needed for each lab. This will also help you with storage and organization and is useful to keep in your prep room to allow for fast lab setup. I like to make the list in Excel, because it helps me keep track of numbers for inventory and reordering purposes.

If you have more time and energy, you can also list the amount you need/have, company and stock number, and type of chemical (oxidizer, acid, base, etc.) for storage purposes. If you can’t get that far right now, don’t worry—you will eventually get there.

From this list, you know what chemicals you need available in your prep room. This probably deviates from what you actually have in there. Making sure you know what you need and how much you have is important so you don’t run out and you know when it’s time to reorder.

Once you have an idea of what chemicals you need, it’s time to get busy in your prep room. This part could take weeks if you only have a few minutes a day, but don’t feel overwhelmed. By taking baby steps and working with the limited time you have, your prep room will eventually be organized to your liking.

Safety labels

One skill many high school science teachers need to refresh is how to read and interpret safety labels and the new safety data sheets (SDSs). I will refer to the Globally Harmonized System (GHS), a universal system designed to provide a consistent method of communicating chemical hazards. Newer labels contain the following information:


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1. Product identifier—typically the IUPAC chemical name, but it can also be a trade name or chemical formula.

2. Signal word—in the GHS system there are two words: “Danger” and “Warning.”

  • “Danger” implies that a chemical is a more immediate or greater danger than “Warning.”
  • “Warning” implies a lesser, though still potentially harmful, risk.

3. Hazard statements—there are 72 individual and 17 combined hazard statements.

  • Each code carries the letter H for hazard statement, followed by three numbers.
  • The first number designates the type of hazard:
    2 for physical hazards
    3 for health hazards
    4 for environmental hazards
  • Two subsequent numbers indicate more specific hazards, e.g., codes 200–210 indicate an explosive physical hazard.

4. Precautionary statements—there are 116 individual and 33 combined precautionary statements.

  • Each code carries the letter P for precautionary statement, followed by three numbers.
  • The first number designates the type of precaution:
    1 for general precautions
    2 for prevention
    3 for response
    4 for storage
    5 for disposal
  • Two subsequent numbers correspond to numbered precautionary statements.

5. Supplier—Flinn Scientific, Ward’s Science, Fisher Scientific, etc.

6. Pictogram—alerts users to hazards to which they may be exposed.

All of the codes and statements are explained in this document on pages 4–9 (hazard) and 13–36 (precautionary). Older chemicals may not have labels that carry all of this safety information, but by looking up the SDS you can find out the specifics for each chemical.

SDSs will replace MSDSs starting in June of 2015. There are 16 parts to the newly designed sheet, but thankfully, OSHA has supplied a quick reference. SDSs contain much of the same information as the labels but include additional information such as storage, accidental release, and first-aid action steps.

I find it helpful to print out the quick reference sheets to take into the lab and prep room with me as I read and sort through chemicals. I only do this for chemicals with unfamiliar properties. However, OSHA does require a full list of SDSs to be present in your laboratory, so keep that in mind when cleaning out and restocking.

Sammye Sigmann, a chemical safety expert, shared some insight on safety labels in an AACT webinar. AACT members can view the archived presentation.

Chemical storage

Now that you are more comfortable reading safety labels, let’s move on to how chemicals should be stored and organized. One of the most important aspects of storage is making sure that incompatible chemicals are not near one another. Many of us probably began with an alphabetically organized prep room. Truthfully, it’s easy to just leave it that way because our demanding schedules don’t allow us to devote much time to reorganize. Also, we forget some of our college training and get busy with grading, teaching, and other responsibilities that come with being a dedicated chemistry teacher. And for those chemistry teachers who never had formal training, perhaps this is your first exposure as to why a prep room should be organized in a particular way.

After teaching for a few years, I found it difficult to even remember what an oxidizer was, let alone why it needed special consideration in storage! Chemical supply catalogs are an excellent resource when (re)learning chemical types but can also be tough to follow. However, a really helpful resource for beginning prep room cleaning is the list of Flinn’s 40 devil chemicals, which identifies the 40 most dangerous chemicals typically found in a school lab. If you have any chemicals on the list, you should think about whether you really need them. If you decide you do, make sure to store them properly. Discarding them isn’t necessarily the easy option, as these chemicals can present disposal challenges (which will be discussed in a future post). The Devil List is printed in the catalog, but you can print your own PDF. I was surprised when I found quite a few of the chemicals on the list hidden in low cabinets. And I was even more surprised to find others located dangerously close to chemicals they are incompatible with!

Organizing chemicals

Once you’re familiar with the worst of the worst (relatively speaking), you can start looking at your chemical inventory in a more focused fashion. There are many tables online that outline compatibility (example). The tables consist of a list of chemicals and those they should not be stored with or near. Lists like this can be especially helpful as you reacquaint yourself with chemical properties. SDSs also contain this information, so if you are uncertain, you can look at those documents for clarification.

I find that it’s easiest for me to organize my chemical inventory on paper first. I organize my spreadsheet of needed chemicals into storage areas; I find it nearly impossible to walk into a stockroom and start rearranging bottles and jars. Once I organize my chemical list, moving chemicals around doesn’t seem like such an ominous task. I don’t have to walk into the prep room second-guessing or questioning the safety of each chemical I touch. The process is smooth and efficient.

If your prep room is improperly organized and scary to approach, I highly recommend you organize it with pencil (or computer) and paper first. This may help you see it’s not an insurmountable task and will certainly be helpful for the next step.

Purging and disposing of chemicals

When you open your cabinets, you will probably notice many chemicals that aren’t on your list of necessary chemicals. I’m not saying to throw them ALL away, but do consider whether they are worth the shelf space. If you believe you possess a chemical you will use in the future, keep it. However, check all of your chemicals for signs of deterioration or contamination. Did a hygroscopic chemical take on water? Has a bottle of solution been stored improperly or exposed to air? Maybe you don’t know how long ago a certain reagent was purchased. In an ideal world, we would know when all of our chemicals were purchased because they would be cataloged as soon as they came in; however, because you probably inherited at least some of your inventory, this probably isn’t the case.

Many chemicals have expiration dates printed on them, whether directly or in code somewhere on the bottle. Fisher Scientific recommends disposing of chemicals after five years. If you have no inventory system, you can check websites for the chemical companies’ current labels. Also, there will be obvious signs if a chemical is really old. In my case, I found chemicals from a local pharmacy. When I contacted the pharmacy, they informed me that they stopped selling chemicals in the 1960s. If labels are missing or faded, it is also a good idea to dispose of them. Regardless, I would encourage you to be ruthless in disposing of questionable chemicals as you clean out your cabinets.

Start with one cabinet or shelf at a time and remove all of the contents. Wipe the shelf clean, and if necessary, put a protective liner on the shelf. For example, I have wooden shelves, and a bottle of potassium hydroxide broke and ruined the wood. It continues to react with the wood years later. In this case, a liner would be important to keep an unwanted side reaction from occurring. Many of us have cabinets and shelving that weren’t originally approved for chemical storage, so if that is your situation, place trays or plastic liners underneath your chemicals.

Categorize your chemicals in two “piles”: keep and toss. If you have the room, simply leave the chemicals you are keeping on a counter or a cart until you have finished purging. If not, place them back on the shelf temporarily. You will find it much easier to organize and store safely once the shelves are clean.

The chemicals in the toss pile will require a bit more thought. Is this a chemical that can be diluted and put down the sink? Can it simply be thrown in the trash can, or maybe sealed in a paint can until Hazmat can get it? Consult SDSs to determine each chemical’s disposal requirements. There’s no quick way to safely carry out this step because each chemical requires a different protocol. In many cases, high schools do not have access to chemical disposal more than once per year, so safe storage is essential in the meantime.

After the shelves are clean, label the shelves so that others can follow your organizational scheme. Start filing chemicals, noting as you go which should be reordered.

Many teachers struggle with how much chemical to order and end up ordering in bulk just in case or because it’s more cost-efficient. This is how we end up with years of unused chemicals. Most teachers probably place one order per year, so it is ideal to determine how much you will need and order just enough. Or implement my rule of thumb and order one-and-a-half times the necessary amount—to account for spillage! Regardless, it is helpful to fill in your chemical spreadsheet with approximate amounts needed and order dates. This will be very helpful for future cleaning projects, as well as for future teachers who may inherit your lab.

How’s it going?

As you clean and organize your lab, let us know how it’s going. Ask any questions you may have or share information you think would be helpful. Pooling our knowledge and resources will help all of us with the challenges associated with chemical clean up, and we can’t do it without you!

Note from the editor:
This article appeared on AACT's blog as a four-part series in February and March; this is a consolidation of those posts in one cohesive article.

Photo Credit: (Top), (Second), Jenny Bishoff (Remaining)