Category: Lab Safety & Environment

Fundamental skills before doing experiments: using a laboratory notebook, pre-lab preparation, percent yield calculations, and finding reliable pre-lab information.

How to Check and Retire Damaged Glassware Safely

Summary
Before you start any experiment, take a moment to inspect your glassware. Any visible crack or chip – anywhere on the piece – is a reason to stop using it. This is especially important for vacuum and thick-walled vessels. Retire damaged items, place broken glass in the correct waste container, and choose appropriate glassware for demanding hot–cold or vacuum work to reduce the risk of cuts and implosions.

1. Why damaged glassware matters

Damaged glassware is more than an aesthetic problem. It adds two kinds of risk to the lab:

  • Cuts and punctures – sharp chips on rims, joints or broken edges can easily cut hands or fingers.
  • Sudden failure during use – cracks can propagate when glass is heated, cooled, clamped or put under vacuum, sometimes leading to breakage or implosion.

The cost of a replacement flask or beaker is always lower than the cost of an injury, lost sample, or damaged equipment. A simple inspection habit before each experiment prevents many avoidable accidents.

2. A simple inspection routine before you use glassware

Do a quick but systematic check before you set up:

2.1 Look along all critical edges

Check every edge that you might touch or that must seal:

  • Rims of beakers, flasks and test tubes
  • Ground-glass joints (inner and outer)
  • Stopcocks and valves
  • Hose barbs, sidearms and adapters

Look for:

  • Chips, missing “bites” of glass
  • Rough or sharp spots
  • White, frosted areas that were not originally ground

2.2 Scan the whole body, not just the rim

Any part of the glass can crack, not only the edge. Inspect:

  • The body of flasks and bottles for straight cracks, curved cracks or “spider-web” patterns
  • The neck and shoulders where the shape changes
  • Side arms and joint transitions, where the wall thickness changes
  • The base for star cracks – radiating lines that start from a point of impact

Rotate the item slowly in good light, or against a dark background, to catch reflections from fine cracks.

2.3 Use your fingers carefully

With clean, dry fingers:

  • Run a fingertip very lightly around rims and joints to feel for nicks
  • Avoid pressing hard or sliding quickly – you are checking, not polishing
  • If a spot feels sharp or irregular, examine it closely in the light

Rule of thumb:

If you can clearly see or feel a crack or chip anywhere on the glass, do not use that item for experiments.

Before you use any piece of glassware, run through this quick checklist:

Check all edges

Check the body and base

Extra care for vacuum and thick-walled glass

3. When a piece must be retired

In a teaching or research lab, it is safer to retire glassware early rather than “see how long it lasts”. Retire an item immediately if you notice:

  • Any visible crack, however short, on the body, neck, joint, side arm or base
  • A chip or missing piece on any rim, ground joint or stopper
  • A star-shaped crack on the bottom or side
  • A joint that no longer seals properly because the glass is visibly worn or chipped
  • Any item that has experienced a strong impact and is now suspected to have hidden damage

For most labs, the safest policy is:

If in doubt, throw it out.

Label suspect glassware clearly (for example, with tape marked “BROKEN / DISCARD”), remove it from the cupboard so it cannot be used by mistake, and move it towards the correct waste route.

4. Special case: vacuum and thick-walled glassware

Vacuum operations and pressure differences place extra stress on glassware.

  • Under reduced pressure, the outside air pushes inwards. Cracks act as stress concentrators, making implosion more likely.
  • Thick-walled glassware such as vacuum flasks, Schlenk lines, cold traps and filter flasks is designed to handle this stress only when it is free of defects.

For vacuum-rated glassware:

  • Inspect before every use – pay special attention to the body, neck and any branches.
  • Never use a piece with visible cracks, chips or star patterns, even if they look small or “stable”.
  • Use guards where available: safety shields, blast screens, or protective cages around large vacuum vessels.
  • Do not rely on tape or plastic film to “hold it together”. These do not restore the strength of the glass.

Once a vacuum vessel has any visible defect, it should be permanently retired from vacuum service. In most labs, the safest approach is to discard it completely rather than downgrade it to non-vacuum use, to avoid confusion later.

Quick question

You are about to set up a vacuum distillation using a thick-walled 100 mL round-bottom flask. When you inspect it, you notice a short, fine crack near the shoulder of the flask that is clearly visible in the light. What should you do?

  1. A. Use the flask anyway but reduce the vacuum level.
  2. B. Wrap tape or film around the crack and then use the flask.
  3. C. Retire the flask from service and choose an undamaged vacuum flask.
Show suggested answer

Retire the flask from service and choose an undamaged vacuum flask.
Any visible crack in a vacuum-rated vessel is a serious hazard, because stress is concentrated at the defect and can lead to implosion under reduced pressure. Tape or lower vacuum do not restore the original strength of the glass. The safest option is to remove the damaged flask from use and replace it with an intact, properly rated vacuum flask.

5. How to deal with damaged or broken glass

5.1 Damaged but still in one piece

If a piece is intact but damaged:

  1. Stop using it immediately.
  2. Mark it clearly (for example, with tape or a label saying “BROKEN / DISCARD”).
  3. Place it in the designated area for broken glass, or in a container waiting to be emptied into the glass waste bin.
  4. Inform the lab supervisor if local rules require it.

Do not put damaged glass back in the cupboard “to think about later”. It will eventually be picked up by someone who assumes it is fine.

5.2 Completely broken glass

When glass breaks:

  • Warn people nearby so they do not step on fragments.
  • Wear appropriate gloves and closed shoes.
  • Use tongs, forceps, a brush and pan, or a piece of stiff cardboard to collect fragments. Avoid picking up shards with bare hands.
  • Place all pieces into the designated glass-waste container – not into normal trash bags, where they can injure cleaning staff.
  • If glass is contaminated with chemicals, follow your lab’s procedure for chemical-contaminated glass waste (for example, labelled glass waste containers or special bags).

A rigid, puncture-resistant glass waste container is standard in most labs. It protects everyone who handles waste downstream.

6. Choosing glassware for demanding heating and cooling

Thermal shock resistance depends mainly on the type of glass. For most high-quality labware, this means borosilicate 3.3 glass, which tolerates heating and cooling better than ordinary soda-lime glass.

Within the same glass type, the way glassware is made also matters:

  • Blown or flame-worked glassware tends to have more uniform wall thickness and smoother transitions between sections. This helps distribute thermal stress more evenly.
  • When such pieces are properly annealed after forming, internal residual stress is reduced, so they are less likely to crack under rapid heating or cooling.

For applications that combine high temperatures with repeated hot–cold cycling – such as reflux, distillation, or heating and then quenching – it is often safer to:

  • Use well-annealed, blown borosilicate glassware explicitly specified for those conditions,
  • Avoid heavy moulded pieces with sharp changes in thickness where thermal stress can concentrate.

This does not mean moulded glassware is unsafe; it is perfectly adequate for many routine tasks. The key is to match the design and specification of the glassware to the temperature and thermal-shock conditions of your experiment, and to continue inspecting pieces regularly over their lifetime.

Why You Must Never Eat, Drink or Mouth-Pipet in the Lab

Summary
In a lab, anything that reaches your mouth can carry invisible chemical or biological contamination. Eating and drinking in the lab, or pipetting by mouth, turns that invisible risk into a direct exposure. Modern lab safety rules ban food and drink in experimental areas, forbid mouth pipetting, and require thorough handwashing before you leave the lab or touch food. Second-hand and returned glassware also demand extra care: treat them as potentially contaminated until they are properly cleaned.

1. How chemicals reach your mouth in a lab

When people think about chemical exposure, they often focus on spills or fumes. But one of the most straightforward and dangerous routes is ingestion – chemicals entering through your mouth and digestive tract.

In a lab, this can happen in several ways:

  • Tasting or “checking by mouth”
    Historically, some chemists really did taste small amounts of substances to identify them. Today, this is recognised as unnecessary and unsafe.
  • Mouth pipetting
    Drawing liquids into a pipette by sucking with your mouth can send the liquid, aerosols or vapour directly into your mouth or throat if you misjudge the volume or lose control.
  • Contaminated hands touching food, drinks or your face
    You handle glassware, reagents, second-hand or returned items, and then:
    • eat a snack,
    • drink water or coffee,
    • touch your lips or wipe your mouth
      without washing your hands thoroughly.
  • Food and drink stored or opened in the lab
    Even if you never “taste chemicals”, food and drink left on lab benches can be contaminated by splashes, vapour, dust or dirty gloves.

The common pattern is simple: any object that lives in the lab environment can carry residues you cannot see.

2. Why labs ban food and drink completely

Most lab safety manuals include a strict rule: no eating, no drinking, no food storage in laboratories. This is not about being strict or unfriendly; it is about breaking the most direct path for ingestion.

2.1 Invisible residues are everywhere

In a lab, many surfaces can carry small amounts of chemicals:

  • The benchtop where you work
  • Glassware, even if it “looks clean”
  • Pipettes, clamps, racks and instruments
  • Your notebook, pens and keyboard if you touch them with contaminated gloves

These residues can be:

  • Organic solvents
  • Corrosive or irritant reagents
  • Heavy metals or other toxic compounds
  • Biological materials in some labs

You cannot see or smell most of these in the small amounts that matter for chronic exposure.

2.2 A real-world lesson: eating after handling glassware

In one glass factory, a worker was asked to check returned glassware that a customer had sent back. He handled the glass instruments with bare hands to inspect them, without knowing exactly what they had been used for or what residues might be present.

After the inspection, he did not wash his hands. He then picked up food and ate. Shortly afterwards, he developed signs of poisoning and later died.

We do not need the exact chemical identity to understand the chain of events:

  1. Returned or second-hand glassware may have unknown residues on the surface.
  2. Handling them with bare hands transfers residue to the skin.
  3. Eating without washing hands transfers residue from skin to mouth.

This kind of tragedy is not dramatic or exotic. It is a series of small, very ordinary decisions:

  • “I’m just touching glass, not chemicals.”
  • “I’ll eat first, wash my hands later.”

The rule “no eating or drinking in the lab, always wash hands before food” exists to break this chain.

2.3 Practical rule

Because of these risks, a safe lab policy is:

  • No food, drink, chewing gum or smoking in experimental areas.
  • No storage of food or drink in lab fridges, freezers or cabinets.
  • Eat and drink only outside the lab, after washing your hands thoroughly with soap and water.

3. Why mouth pipetting is completely banned

Mouth pipetting once was common in chemistry and biology labs. Today, it is recognised as a completely unacceptable practice.

3.1 What goes wrong when you pipet by mouth

When you suck on a pipette:

  • The liquid is very close to your mouth.
  • If you misjudge the suction or the liquid “jumps”, it can enter your mouth or throat.
  • Even if you spit it out quickly, your lips and mucous membranes have already been exposed.

In some cases, droplets or aerosols may enter your airway before you even notice.

3.2 The types of risk

The liquid you are pipetting might be:

  • A toxic organic solvent
  • A corrosive acid or base
  • A solution containing heavy metals
  • A biological sample carrying infectious agents

Historically, some laboratory-acquired infections and poisonings have been linked to mouth pipetting. This is why modern safety standards and institutional rules are unanimous: mouth pipetting is forbidden in professional labs, teaching labs and serious small labs.

3.3 Safer alternatives

Modern labs have simple tools that make mouth pipetting unnecessary:

  • Rubber pipette bulbs
  • Manual pipette controllers
  • Adjustable volume micropipettes with disposable tips

These devices:

  • Keep liquids away from your mouth
  • Give you much better control over volume
  • Are inexpensive compared to the cost of an incident

A good habit is:

If you ever see mouth pipetting in a lab, treat it as an urgent safety issue, not a matter of “style” or “speed”.

4. Second-hand and returned glassware: treat as “unknown”

Second-hand lab glassware and customer returns can be valuable resources, but they also carry invisible history.

You often do not know:

  • Exactly what was in them last time
  • Whether they were used correctly or misused as temporary containers
  • Whether residues have dried on surfaces, joints or threads

4.1 Handling second-hand or returned glassware

When you unpack or inspect second-hand or returned glass:

  • Assume that it may carry unknown contamination.
  • Whenever possible, wear appropriate gloves.
  • Avoid touching your face, phone or personal items during inspection.
  • After handling, wash your hands thoroughly before eating, drinking or leaving for a break.

This applies both in a lab that buys second-hand glassware and in a glassware factory or warehouse that handles returns.

4.2 Cleaning before use in experiments

Before using second-hand or returned glassware in experiments:

  • Put it through a thorough cleaning cycle:
    • Suitable detergent wash
    • Multiple rinses with tap water and then deionised/distilled water
    • Special cleaning procedures as required by your lab
  • If the previous use is unclear and the potential risk is high, your lab may decide to discard the item rather than reuse it.

A simple principle is:

Treat any glassware of unknown history as a potential chemical container until it has been properly cleaned.

5. Building safer everyday habits

Rules only help if they translate into daily habits. The key behaviours for reducing ingestion risk are simple but powerful:

5.1 For eating and drinking

  • Keep all food and drink out of the lab.
  • Never store food or beverages in lab refrigerators or freezers.
  • Before eating, drinking or smoking:
    • Leave the lab
    • Remove gloves and other contaminated PPE
    • Wash your hands thoroughly with soap and water

5.2 For pipetting and liquid handling

  • Never pipet by mouth, even “just water” – habits transfer across tasks.
  • Use pipette bulbs, manual controllers or micropipettes.
  • Store pipetting devices and tips in a clean area, away from direct contamination.
  • Train new lab members explicitly: “We do not mouth pipet, ever.”

5.3 For second-hand and returned glassware

  • Treat unknown glassware as contaminated until cleaned.
  • Wear gloves when inspecting or sorting.
  • Wash your hands after handling, before any break or meal.
  • Do not assume that “it’s just glass” and therefore safe.

Small actions repeated every day—no food in the lab, no mouth pipetting, washing hands—create a long-term barrier against serious incidents.

6.Checklist: before you eat, drink or leave the lab

Before you eat, drink or leave the lab, run through this quick checklist:

Have I been in contact with lab surfaces or materials?

Am I about to eat or drink?

For pipetting

7. Mini quiz: what is the real problem?

Mini quiz

Which of the following behaviours is clearly unsafe because of ingestion risk?



Show suggested answer

Inspecting returned lab glassware with bare hands in the lab and then eating a snack without washing your hands.
Returned or second-hand glassware may carry unknown chemical residues on their surfaces. Handling them with bare hands and then eating without washing transfers any contamination directly to your mouth. New glassware opened in a clean office after handwashing, and properly gloved work with sealed bottles followed by glove removal, are much lower-risk behaviours when done correctly.

8. Safety note

Information on ChemNorth is for educational purposes and for small-lab guidance. Always follow your institution’s safety rules and local regulations. If you are unsure whether a behaviour is safe, ask your instructor, lab supervisor or safety officer before proceeding.

How to Break and Insert Glass Tubing Safely in the Lab

Summary
Cutting glass tubing and inserting glass into rubber or cork stoppers are common tasks in teaching labs, but they are also a frequent cause of hand injuries. To work safely, always score and wet the glass before breaking it, wrap it in a towel or tissue when snapping, lubricate the end before insertion, and hold the glass close to the stopper while rotating gently. Never push hard on un-scored glass or hold the far end of the tube while forcing it through a stopper.

Glass tubing, thermometers and adapters are used everywhere in an organic lab. Preparing them correctly is routine work, but doing it carelessly can send broken glass into the palm of your hand. This article explains safe, step-by-step methods for breaking glass and inserting it into stoppers.

1. Why these tasks cause so many injuries

Typical injury patterns include:

  • Trying to snap un-scored glass tubing by brute force;
  • Holding the far end of a thermometer or tube while pushing it through a tight stopper;
  • Handling glass with bare hands when it suddenly breaks.

The common feature is poor control over where the force goes. Safe techniques help you control the break and keep your hands behind the line of force.

2. How to break glass tubing safely

2.1 Tools and preparation

You will typically need:

  • A glass file, glass-cutting tool or triangular file;
  • A drop of water or glycerol;
  • A towel or several layers of paper tissue.

2.2 Step-by-step procedure

  1. Mark the length you need on the glass.
  2. Score a small, clean line around the tube at that point using the file. You do not need to cut deeply; one firm stroke is usually enough.
  3. Wet the score line with a drop of water to help the crack start smoothly.
  4. Hold the tube with both hands, wrapped in a towel or paper tissue, with your thumbs placed opposite the score line.
  5. Gently bend the glass away from the score until it snaps along the line.

Do not twist or crush the glass. The force should be slow and controlled.

2.3 After the break

  • Smooth any sharp edges with fine sandpaper or a fire-polishing step if your instructor allows it.
  • Dispose of unwanted off-cuts in the broken-glass container, not in normal trash.

3. How to insert glass into rubber or cork stoppers

3.1 Why this step is risky

When you push a long piece of glass through a tight stopper, the stress concentrates near the point where it enters the stopper. If the glass breaks, the broken end can be driven toward the hand that is pushing.

3.2 Safer technique

  1. Lubricate the end of the glass with a drop of water or glycerol.
  2. Hold the stopper in one hand.
  3. With the other hand, hold the glass close to the end that enters the stopper, not at the far end.
  4. Push the glass in while rotating the stopper gently, applying slow, even pressure.
  5. Stop if resistance is very high and ask for a larger bore hole or a different adapter.

Never use sudden, strong force. Never hold the glass far away and “ram” it through.

4. Inspecting and using prepared glass

After you have prepared your glass:

  • Check that the exposed ends are reasonably smooth and free of large chips.
  • Make sure the glass sits straight in the stopper or adapter; avoid forcing it into distorted angles.
  • Handle long assemblies carefully and support them with clamps where appropriate.

5. Checklist: before, during and after

Before

  • I have the right diameter of glass tubing or thermometer.
  • I have a file, lubricant, and towel or tissue ready.
  • I know exactly how long the piece needs to be.

During

  • I always score before breaking glass.
  • I wrap the glass and keep my hands behind the line of force.
  • I hold glass close to the stopper end when inserting and rotate gently.

After

  • Off-cuts go into the broken-glass container.
  • Edges are smoothed if necessary and allowed by the lab.
  • Completed assemblies are handled and clamped carefully.

6. Safety note

Information on ChemNorth is for educational purposes and small-lab guidance. Always follow your institution’s safety rules and local regulations, and ask your instructor or safety officer if you are unsure about a procedure.

How to Use Heat Safely in an Organic Chemistry Lab

Summary
Heating is essential in organic chemistry, but it is also one of the main sources of fires and burns in the lab. To use heat safely, avoid open flames around flammable solvents, prefer hot plates and heating mantles, keep solvent bottles and waste containers away from hot surfaces, and never leave an active heater unattended. Always check glassware for cracks before heating and allow hot equipment to cool before moving or cleaning it.

When you begin experimental organic chemistry, you quickly discover that many reactions and procedures require heat. Refluxing, distillation, evaporation, and drying all depend on controlled heating. At the same time, heating is closely linked to fires, burns, and broken glassware. This article gives you a practical guide to using heat with the lowest reasonable risk in a teaching or small organic lab.

1. Why open flames are rarely a good idea

In an organic lab, open flames (Bunsen burners, alcohol lamps, lighters) are almost always the least safe heating option.

1.1 Flammable vapours travel farther than you think

  • Many organic solvents (diethyl ether, pentane, hexane, acetone, etc.) have low boiling points and high vapour pressures.
  • Their vapours are often heavier than air and can flow along the bench or near the floor.
  • A flame several metres away can still ignite a vapour cloud that drifts past it.

Because of this behaviour, many organic labs adopt a simple rule:

No open flames when flammable solvents are in use.

1.2 When a flame might still appear

If your lab still uses Bunsen burners, they are usually reserved for:

  • Briefly flaming glassware to dry it;
  • Sterilisation in microbiology work (less common in organic labs).

Even in these cases, flames should be used far from solvent bottles and waste containers, and only when your instructor confirms it is safe.

2. Safer options: hot plates and heating mantles

Hot plates and heating mantles remove the naked flame, but they are not risk-free.

2.1 Hot plates

Hot plates are good for:

  • Gentle heating of beakers and flasks;
  • Combining heating and magnetic stirring.

Safer habits:

  • Use appropriate support: place flasks in a beaker or on a ceramic pad when needed, not directly on bare metal if the design does not allow it.
  • Keep the area around the hot plate clear of solvent bottles, paper towels, and plastic items.
  • Turn the control to low or off before plugging in or unplugging.

2.2 Heating mantles

Heating mantles are designed to heat round-bottom flasks more evenly than hot plates.

Safer habits:

  • Use a mantle that fits the flask size properly; avoid “cramming” a larger flask into a smaller mantle.
  • Always support the flask with a clamp and stand, not just resting in the mantle.
  • Do not let liquid overflow into the mantle. If it happens, turn off the power and report it.

Quick question

You finish a reflux experiment and turn off the heating mantle. The round-bottom flask is still very hot and contains flammable solvent. What is the safest thing to do next?

  1. A. Immediately remove the flask from the mantle with bare hands so it cools faster.
  2. B. Leave the flask supported and let it cool in place before handling it.
  3. C. Move the hot flask quickly to another bench to free the mantle.
Show suggested answer

Leave the flask supported and let it cool in place before handling it.
Hot glassware can cause burns and is more likely to break if moved while very hot. Keeping the flask clamped and supported reduces the chance of spills or sudden breakage while the solvent and glass cool down.

3. Preventing fires when heating solvents

Most heating-related fires share a few common features. You can avoid many of them by planning ahead.

3.1 Keep flammable liquids away from hot surfaces

Before you turn on any heater, check:

  • Are solvent bottles stored away from the hot plate or mantle?
  • Is your waste container located somewhere cooler and safer?
  • Is there any spill or residue on the hot surface from a previous user?

If a spill occurs:

  • Turn off the heater if it is safe to do so.
  • Allow the surface to cool if necessary.
  • Wipe the area carefully with appropriate materials, disposing of them as chemical waste if required.

3.2 Control boiling and bumping

Uncontrolled boiling can throw hot liquid out of the flask:

  • Use boiling chips or a stir bar when appropriate.
  • Start with a low heat setting and increase gradually.
  • Never fill a flask more than about half full for boiling or reflux.

4. Glassware and heat: avoiding cracks and burns

4.1 Check glassware before heating

Heating cracked or chipped glassware increases the chance of sudden failure.

Before you heat:

  • Inspect the rim, body, and any joints for cracks or chips.
  • Do not use flawed glassware, especially under reflux, distillation, or vacuum.

4.2 Handling hot glassware

Hot glass often looks exactly like cold glass.

  • Assume glassware on or near heaters is hot.
  • Use heat-resistant gloves or tongs when moving recently heated items.
  • Allow glass to cool on a heat-resistant surface before washing or storing.

5. Checklist: heat safety before, during and after

Before, during and after using heat, you can use this quick checklist:

Before heating

While heating

After heating

6. Safety note

Information on ChemNorth is for educational purposes and small-lab guidance. Always follow your institution’s safety rules and local regulations, and ask your instructor or safety officer if you are unsure about a procedure.

Mini quiz

Which situation is most clearly unsafe in an organic chemistry lab?



Show suggested answer

Placing an open bottle of diethyl ether next to a hot plate that is turned on.
Diethyl ether is a very volatile and highly flammable solvent. Its vapours can travel to the hot surface and ignite, even if the flame or heating element is not in direct contact with the liquid. The other two situations are normally acceptable in a well-managed lab.

Your First Organic Chemistry Lab: A Practical Safety Briefing

Summary
To stay safe in an organic chemistry lab, you should always wear a lab coat, goggles and suitable gloves, keep flames and hot surfaces away from flammable solvents, and handle volatile or toxic chemicals in a fume hood. Never eat, drink or pipet by mouth in the lab, wash your hands when you finish, and avoid using damaged glassware or electrical equipment.

When you walk into an organic chemistry lab for the first time, the benches, glassware and instruments can feel exciting and intimidating at the same time.
This article is meant to be quiet, practical “pre-reading” before you ever light a heater or pour a solvent.

It does not replace your department’s official safety rules. Instead, it helps you understand why those rules exist, and what is most likely to go wrong if you ignore them.

1. Three common types of lab accidents

Most accidents in the organic lab fall into three broad groups:

  1. Fires and explosions – ignition of flammable vapours or reactive chemicals.
  2. Cuts and mechanical injuries – mainly from broken or mishandled glassware.
  3. Exposure to toxic materials – by inhalation, ingestion, or skin absorption.

Once you start noticing which group a situation belongs to, it becomes much easier to see danger coming a few steps earlier.

2. Fires and explosions: controlling ignition sources

Organic chemistry uses a lot of volatile, flammable liquids. Their vapours are heavier than air and can travel along the bench or near the floor to find a flame or spark.

The safest mindset is:

Assume flammable vapour is present whenever you are using low-boiling organic solvents.

The main ignition sources in a teaching lab are:

2.1 Open flames

Open flames include Bunsen burners, alcohol lamps, matches and lighters.

  • Vapours from solvents like diethyl ether, pentane or acetone can ignite even when the flame is a few metres away.
  • For this reason, many organic labs do not allow open flames at all when flammable solvents are in use.

If your lab still uses Bunsen burners, they should only be lit when your instructor explicitly allows it, and never near open bottles of solvent or waste containers.

2.2 Hot surfaces

Hot plates and heating mantles have no visible flame, but their surfaces can easily ignite solvent spilled on them.

Typical problems:

  • A reaction mixture bumps out of a flask onto a hot plate.
  • Someone sets a solvent bottle or beaker directly on a hot heating mantle.
  • The thermostat on a hot plate switches on and off, and the internal spark ignites vapour from an open container nearby.

Practical habits:

  • Keep solvent bottles and waste containers away from heaters.
  • Wipe up spills immediately once equipment has cooled enough to do so.
  • Turn off heaters as soon as you are finished with them.

2.3 Faulty electrical equipment

Frayed power cords, loose plugs, and damaged sockets can produce sparks or overheat.

  • Never use equipment with exposed wires, cracked plugs or scorched insulation.
  • If you notice a problem, unplug the device and report it instead of “making it work this one time”.

2.4 Chemical fires

Some reactions themselves generate enough heat or gas to ignite nearby material:

  • Very reactive metals (such as sodium) reacting with water and releasing hydrogen gas.
  • Strong oxidizing agents mixed with organic material.

You will normally only perform such reactions under close supervision. Read the pre-lab notes carefully and understand where the heat and gas are coming from.

3. Cuts and mechanical injuries: working safely with glass

Glassware is at the heart of the organic lab, and also a major source of minor injuries.

3.1 Breaking glass rods or tubing

When you need to cut glass tubing, the safe method is:

  1. Score a small line around the glass with a file or glass-cutting tool.
  2. Wet the score line with a drop of water to help the crack start cleanly.
  3. Hold the tube with both hands, wrapped in a towel or paper tissue, with thumbs placed opposite the score line.
  4. Gently bend the glass away from the score until it snaps along the line.

Never try to “snap” un-scored glass by brute force – it tends to shatter unpredictably.

3.2 Inserting glass into stoppers

Thermometers and glass tubes are often fitted into rubber or cork stoppers. Done badly, this is a classic way to drive broken glass into the palm of your hand.

Safer technique:

  • Lubricate the end of the glass with a drop of water or glycerol.
  • Hold the stopper in one hand and the glass close to the end that enters the stopper with the other.
  • Rotate the stopper gently while pushing slowly.
  • Never hold the glass far from the stopper and push hard – if it breaks, the broken end can be forced into your hand.

3.3 Chipped or cracked glassware

Before you use any beaker, flask or funnel, quickly check:

  • Are the rims smooth?
  • Is there any crack along the body or near the joint?

If you find chips or cracks:

  • Do not use the item, especially under vacuum or heat.
  • Place it in the designated broken-glass container or follow your lab’s procedure.

A small chip on the lip of a beaker is still sharp enough to slice your finger.

4. Exposure to toxic materials

Even if nothing catches fire and no glass breaks, you can still be harmed by breathing, swallowing or absorbing chemicals.

4.1 Inhalation: use the fume hood

Many organic liquids evaporate readily and have irritating or toxic vapours.

  • A fume hood is designed to remove these vapours from the lab air.
  • Whenever you work with volatile, smelly or toxic substances, assume they belong in the hood unless your instructor explicitly says otherwise.

Practical points:

  • Make sure the hood is on and drawing air before you start.
  • Work at least a hand-span inside the opening, not right at the edge.
  • Keep the sash at the recommended height to maintain good airflow.

4.2 Ingestion: keep chemistry out of your mouth

Ingestion accidents are almost always preventable:

  • Never taste any substance in the lab.
  • Never pipet liquids by mouth – use a pipet bulb or mechanical pipettor.
  • Do not eat or drink in the lab, and do not store food in lab refrigerators.
  • At the end of the session, wash your hands thoroughly with soap and water.

Any food, drink, or lip balm used in the lab can easily become contaminated.

4.3 Skin absorption: protect your skin

Many organic compounds can pass through the skin, especially if they are non-polar and your gloves are not resistant to them.

  • Wear appropriate protective gloves when handling liquids or solids that could irritate or be absorbed through the skin.
  • If a chemical is spilled on your skin:
    • Rinse the area immediately with plenty of water for at least 10–15 minutes.
    • Inform your instructor, even if it doesn’t hurt at once.

Gloves are not all the same. Later, you will learn how to match glove materials (for example, nitrile vs latex) to the solvents you use.

5. A short checklist for your first lab session

Before or during your first organic lab, make sure you can answer these:

1. Do I know where to find…

2. Am I using heat safely?

3. Am I handling glassware correctly?

4. Am I limiting my exposure to chemicals?

6. Final thoughts

The organic chemistry lab will always contain some level of risk, simply because we work with energetic reactions and active molecules.
But with a basic understanding of how accidents actually happen—and with a few good habits—you can keep that risk low enough to learn and explore with confidence.

In future ChemNorth articles, we will look more closely at specific topics: how to choose safe heating equipment, how to handle broken glass, and how to work effectively in the fume hood.

For now, bring this safety briefing with you in your mind the next time you step into the lab. It is the quiet foundation under every successful experiment.