Chapter 2. Laboratory Safety

This is a short chapter, but a very important one. Many of the experiments described in this book use chemicals, such as strong acids and bases, that are dangerous if handled improperly. Some experiments use open flame or other heat sources, and nearly all of the experiments use glassware.

Working in a home chemistry lab has its dangers, but then so does driving a car. And, just as you must remain constantly alert while driving, you must remain constantly alert while working in a home chemistry lab.

It’s important to keep things in perspective. More serious injuries occur every year among a few hundred thousand high-school football players than have ever occurred in total among millions upon millions of home chemists in the 200-year history of home chemistry labs. Statistically, students are much, much safer working in a home chemistry lab than they are out skateboarding or riding bicycles.

Most injuries that occur in home chemistry labs are minor and easily avoidable. Among the most common are nicks from broken or chipped glassware and minor burns. Serious injuries are very rare. When they do occur, it’s nearly always because someone did something incredibly stupid, such as using a flammable solvent near an open flame or absentmindedly taking a swig from a beaker full of a toxic liquid. (That’s why one of the rules of laboratory safety is never to smoke, drink, or eat in the lab.)

The primary goal of laboratory safety rules is to prevent injuries. Knowing and following the rules minimizes the likelihood of accidents, and helps ensure that any accidents that do occur will be minor ones.

Dr. Paul Jones Comments

Everyone rightly treats strong acids with great respect, but many students handle strong bases casually. That’s a very dangerous practice. Strong bases, such as solutions of sodium hydroxide, can blind you in literally seconds. Treat every chemical as potentially hazardous, and always wear splash goggles.

Laboratory Safety Rules We Recommend

Prepare Properly

All Laboratory Activities Must be Supervised by a Responsible Adult

• Direct adult supervision is mandatory for all of the activities in this book. This adult must review each activity before it is started, understand the potential dangers of that activity and the steps required to minimize or eliminate those dangers, and be present during the activity from start to finish. Although the adult is ultimately responsible for safety, students must also understand the potential dangers and the procedures that should be used to minimize risk.

Familiarize Yourself with Safety Procedures and Equipment

• Think about how to respond to accidents before they happen. Have a fire extinguisher and first-aid kit readily available and a telephone nearby in case you need to summon assistance. Know and practice first-aid procedures, particularly those required to deal with burns and cuts. Paul Jones notes, “Since getting my cell phone, I’ve started to always have it on me in the lab. Seems easy enough to do and then I wouldn’t have to find a phone if something bad happened.”

• One of the most important safety items in a home lab is the cold water faucet. If you burn yourself, immediately (seconds count) flood the burned area with cold tap water for several minutes to minimize the damage done by the burn. If you spill a chemical on yourself, immediately rinse the chemical off with cold tap water, and keep rinsing for several minutes. Ideally, every lab should have an eyewash station, but most home chemistry labs do not. If you get any chemical in your eyes, immediately turn the cold tap on full and flood your eyes until help arrives.

• Keep a large container of baking soda on hand to deal with acid spills, and a large container of vinegar to deal with base spills.

Always Read the MSDS for Every Chemical that You Will Use in a Laboratory Session

• The MSDS (Material Safety Data Sheet) is a concise document that lists the specific characteristics and hazards of a chemical. Always read the MSDS for every chemical that is to be used in a lab session. If an MSDS was not supplied with the chemical, locate one on the Internet. For example, before you use potassium chromate in an experiment, do a Google search using the search terms “potassium chromate” and “MSDS.”

Organize Your Work Area

• Keep your lab bench and other work areas clean and uncluttered—before, during, and after laboratory sessions. Every laboratory session should begin and end with your glassware, chemicals, and laboratory equipment clean and stored properly.

Dress Properly

Wear Approved Eye Protection at All Times

• Everyone present in the lab must at all times wear splash goggles that comply with the ANSI Z87.1 standard. Standard eyeglasses or shop goggles do not provide adequate protection, because they are not designed to prevent splashed liquids from getting into your eyes. Eyeglasses may be worn under the goggles, but contact lenses are not permitted in the lab. (Corrosive chemicals can be trapped between a contact lens and your eye, making it difficult to flush the corrosive chemical away.)

Wear Protective Gloves and Clothing

• Never allow laboratory chemicals to contact your bare skin. When you handle chemicals, particularly corrosive or toxic chemicals or those that can be absorbed through the skin, wear gloves of latex, nitrile, vinyl, or another chemical-resistant material. (Ansell gloves has a pretty good table that ranks the chemical resistance of various gloving materials: http://www.ansellpro.com/download/Ansell_7thEditionChemicalResistanceGuide.pdf). Wear long pants, a long-sleeved shirt, and leather shoes or boots that fully cover your feet (not sandals). Avoid loose sleeves. To protect yourself and your clothing, wear a lab coat or a lab apron made of vinyl or another resistant material. Wear a disposable respirator mask when you handle chemicals that are toxic by inhalation.

Avoid Laboratory Hazards

Avoid Chemical Hazards

• Never taste any laboratory chemical or sniff it directly. (Use your hand to waft the odor toward your nose.) Never use your mouth to fill a pipette. When you heat a test tube or flask, make sure the mouth points in a safe direction. Always use a boiling chip or stirring rod to prevent liquids from boiling over and being ejected from the container. Never carry open containers of chemicals around the lab. Always dilute strong acids and bases by adding the concentrated solution or solid chemical to water slowly and with stirring. Doing the converse can cause the liquid to boil violently and be ejected from the container. Use the smallest quantities of chemicals that will accomplish your goal. In particular, the first time you run a reaction, do so on a small scale. If a reaction is unexpectedly vigorous, it’s better if it happens with 5 mL of chemicals in a small test tube than 500 mL in a large beaker.

Dr. Paul Jones Comments

Although none of the lab sessions in this book require putting glassware under a vacuum, if you do so for one of your own experiments, always use a polycarbonate explosion shield between yourself and the glassware. Even high-quality glassware that appears undamaged can implode under vacuum, spraying glass shards at high velocity.

Avoid Fire Hazards

• Never handle flammable liquids or gases in an area where an open flame or sparks might ignite them. Extinguish burners as soon as you finish using them. Do not refuel a burner until it has cooled completely. If you have long hair, tie it back or tuck it up under a cap, particularly if you are working near an open flame.

Avoid Glassware Hazards

• Assume all glassware is hot until you are certain otherwise. Examine all glassware before you use it, and particularly before you heat it. Discard any glassware that is cracked, chipped, or otherwise damaged. Learn the proper technique for cutting and shaping glass tubing, and make sure to fire-polish all sharp ends.

Don’t Do Stupid Things

Never Eat, Drink, or Smoke in the Laboratory

• All laboratory chemicals should be considered toxic by ingestion, and the best way to avoid ingesting chemicals is to keep your mouth closed. Eating or drinking (even water) in the lab is very risky behavior. A moment’s inattention can have tragic results. Smoking violates two major lab safety rules: putting anything in your mouth is a major no-no, as is carrying an open flame around the lab.

Never Work Alone in the Laboratory

• No one, adult or student, should ever work alone in the laboratory. Even if the experimenter is adult, there must at least be another adult within earshot who is able to respond quickly in an emergency.

No Horsing Around

• A lab isn’t the place for practical jokes or acting out, or for that matter for catching up on gossip or talking about last night’s football game. When you’re in the lab, you should have your mind on lab work, period.

Never Combine Chemicals Arbitrarily

• Combining chemicals arbitrarily is among the most frequent causes of serious accidents in home chemistry labs. Some people seem compelled to mix chemicals more or less randomly, just to see what happens. Sometimes they get more than they bargained for.

Don’t Make Explosives

• Yes, I know. One thing that nearly all home chemists have in common is the gene that compels us to make stuff that goes boom, and the louder the better. Resist the temptation. In addition to the obvious danger of losing some fingers—or your head—you risk having DHS agents kick down your door and cart you off to prison. Years ago, it was a rite of passage for home chemists to manufacture explosives, from black powder to nitroglycerin to acetone peroxide. Most (not all) of us survived unscathed, and thought no more about it. The authorities weren’t thrilled about kids blowing stuff up, but they generally resigned themselves to the fact that “boys will be boys.” No more. If you’re caught making explosives nowadays—and you probably will be caught if you try it—the best you can hope for is a big fine, and that’s only if you can afford a good lawyer. Just don’t do it.

Laboratory safety is mainly a matter of common sense. Think about what you’re going to do before you do it. Work carefully. Deal with minor problems before they become major problems. Keep safety constantly in mind, and chances are good that any problems you have will be very minor ones.