Laboratory tools: names, pictures and what each one is used for

Which glassware measures, and which only holds

This is the distinction that costs students the most marks, and it is invisible unless somebody points it out. A beaker and a measuring cylinder both have scales printed on them, and they are not remotely equally accurate.

A beaker is a container. Its graduations are approximate and there for convenience, typically within about five percent, which is useless for anything quantitative. A measuring cylinder is a measuring instrument, accurate to around one percent. A volumetric flask or a pipette is better again, accurate to a fraction of a percent, because it measures one single volume rather than a range.

So the rule is simple: if the number matters, do not measure it in a beaker. Use the least convenient piece of glassware that is accurate enough, because convenience and accuracy pull in opposite directions here.

Beakers hold, cylinders measure

Beaker graduations are approximate. If a volume appears in your results, it did not come from a beaker.

One volume beats a range

A volumetric flask or pipette measures a single fixed volume very accurately. That is why it has one line.

Read at eye level, from the meniscus bottom

Read the bottom of the curve for water, at eye level. Looking down adds a consistent error to every reading.

Know whether it is TC or TD

To Contain holds that volume, To Deliver pours it out. A TD pipette leaves a little behind on purpose, so never blow it out.

Never heat volumetric glassware

Heat changes its calibration permanently. Volumetric flasks and pipettes are not for warming anything.

Match the size to the volume

Measuring 5 ml in a 250 ml cylinder is far less accurate than in a 10 ml one. Use the smallest that fits.

Heating without breaking or burning anything

Heat is where laboratory accidents concentrate, and the causes are consistent and avoidable.

Glass breaks from thermal shock, meaning a sudden change in temperature or heat applied unevenly to one spot. That is why you use borosilicate glass, spread the heat with a gauze, and never put hot glass straight onto a cold bench or into cold water.

The other classic is superheating: a liquid heated smoothly past its boiling point without bubbling, which then erupts all at once when it is disturbed. Anti bumping granules or a stirrer bar prevent it, and pointing a heated tube away from everybody prevents the consequences.

Borosilicate glass for anything heated

It tolerates thermal change. Ordinary soda glass cracks, and a cracked vessel fails while it is full and hot.

Spread the heat with a gauze

A flame on one spot of a beaker base cracks it. The gauze distributes it across the whole bottom.

Anti bumping granules in anything boiling

They give bubbles somewhere to form, which stops a superheated liquid erupting out of the flask in one go.

Never seal a heated container

Pressure has nowhere to go and the vessel becomes a bomb. Always leave a vent or an open path.

Point a heated test tube away from people

Including yourself. Contents can shoot several feet out of the mouth without warning.

Hot glass looks exactly like cold glass

There is no visual difference. Use tongs, and put it on a mat rather than a cold bench.

Contamination, and why cleaning is part of the method

A surprising share of unexplained results are contamination rather than bad technique. Glassware carries traces of whatever was in it last, and traces are enough to change a titration or ruin a culture.

Two habits deal with most of it. Rinse glassware with the solution you are about to put in it, not just with water, because a water film dilutes your reagent by an unknown amount. And never return unused reagent to the stock bottle, since whatever it picked up in your glassware then contaminates everybody's supply.

The other half is not letting things touch. A pipette tip against the bench, a stopper laid face down, a spatula used for two chemicals: each is a route for contamination that looks like nothing at the time.

Rinse with the solution, not just water

A film of water in a burette dilutes the first readings by an unknown amount. Rinse with what is going in.

Never pour reagent back into the stock

It contaminates the whole bottle for everyone. Pour what you need, and dispose of the excess properly.

One spatula per chemical

A shared spatula transfers traces between containers, and the contamination follows into every later experiment.

Stoppers face up, or held

A stopper laid face down on the bench picks up whatever is there and carries it back into the bottle.

Label everything immediately

An unlabelled beaker is waste, because you can no longer trust what is in it. Write it as you pour.

Dry does not mean clean

A dry residue is still a residue. Wash, rinse with distilled water, then dry.

The apparatus most practical work is built from

Measuring and holding

Beakers, conical flasks, measuring cylinders, test tubes and a rack, a funnel, a stirring rod, a spatula and a wash bottle. Almost every experiment uses these.

Heating

A Bunsen burner, a tripod, a gauze, a heatproof mat, tongs and a thermometer. Or a hot plate, which is safer and slower.

Quantitative work

A balance, volumetric flasks, pipettes with a filler, a burette and clamp stand, and a white tile to see the endpoint against.

Safety, before any of it

Goggles, a lab coat, gloves suited to the chemical, access to a fume cupboard, an eyewash station and a spill kit. These are not optional extras.

Mistakes that spoil results or cause accidents

Measuring an important volume in a beaker

Beaker graduations are approximate. Anything that appears in your calculations needs a cylinder, pipette or volumetric flask.

Reading a scale from above or below

Parallax adds a consistent error to every single reading. Eye level, at the bottom of the meniscus.

Pipetting by mouth

Never, under any circumstances, with anything. A pipette filler exists precisely so this is unnecessary.

Heating a sealed vessel

Pressure builds with nowhere to go. This is how glassware becomes shrapnel.

Adding water to concentrated acid

It boils and spits acid back at you. Always acid into water, slowly, and with stirring.

No anti bumping granules when boiling

A superheated liquid erupts out of the flask all at once, usually across the bench.

Returning excess reagent to the bottle

It contaminates the stock for everyone who uses it afterwards.

Wearing gloves that do not suit the chemical

Some solvents pass straight through nitrile. The wrong glove holds the chemical against your skin.

Not knowing where the safety equipment is

Eyewash, shower, extinguisher and spill kit. In an emergency there is no time to look for them.

Looking after laboratory apparatus

Wash glassware immediately after use

Dried residue is far harder to shift, and some residues attack glass over time.

Rinse with distilled water last

Tap water leaves dissolved solids as it dries, which is a contaminant in the next experiment.

Dry inverted on a rack

Air dry rather than towel dry, since a cloth leaves fibres and whatever it last touched.

Never heat or oven dry volumetric glassware

It is calibrated, and heat changes that calibration permanently.

Check glassware for cracks before use

A star crack or chip fails under heat or vacuum. Discard it rather than getting one more use out of it.

Keep the balance clean, level and closed

Draughts and spilled powder are the two things that make an accurate balance read inaccurately.

Cover the microscope and store objectives dry

Dust on a lens is the commonest reason an image will not resolve, and immersion oil left on hardens.

Frequently asked questions

What are the basic laboratory tools?

Beakers, conical flasks, measuring cylinders, test tubes and a rack, a funnel, a stirring rod, a spatula, a wash bottle, a Bunsen burner with tripod and gauze, tongs, a thermometer and a balance. Plus goggles and a lab coat, which come before any of it.

What is the difference between a beaker and a measuring cylinder?

A beaker is a container whose graduations are approximate, typically within about five percent. A measuring cylinder is a measuring instrument accurate to around one percent. If a volume appears in your results, it should not have been measured in a beaker.

What is the difference between a conical flask and a volumetric flask?

A conical flask, or Erlenmeyer, has sloping sides for swirling without spilling, and is used for titrations and mixing. A volumetric flask has a long neck with a single calibration line and measures one exact volume, used for making up standard solutions.

How do you read a meniscus correctly?

At eye level, taking the reading from the bottom of the curve for water and most aqueous solutions. Reading from above or below introduces parallax error, which is consistent rather than random, so it biases every measurement the same way.

What does TC and TD mean on glassware?

To Contain and To Deliver. TC glassware holds that volume when filled to the line. TD glassware delivers that volume when poured out, and deliberately retains a small film, which is why you must never blow out the last drop from a TD pipette.

Why do you use a gauze when heating a beaker?

To spread the heat across the whole base. A flame concentrated on one spot heats the glass unevenly, and the resulting thermal stress cracks it, usually while it is full of hot liquid.

What are anti bumping granules for?

They give bubbles a place to form so a liquid boils steadily. Without them a liquid can superheat past its boiling point without bubbling and then erupt all at once, throwing the contents out of the flask.

Why must you never pipette by mouth?

Because you can ingest the contents, and even apparently harmless solutions may be contaminated. A pipette filler or bulb costs very little and removes the risk entirely. This is one of the few absolute rules in a laboratory.

Do you add acid to water or water to acid?

Always acid to water, slowly and with stirring. Diluting concentrated acid releases a lot of heat, and adding water to acid concentrates that heat at the surface, which makes it boil and spit acid back out.

What is the difference between a pipette and a burette?

A pipette delivers one fixed volume accurately. A burette delivers a variable volume and lets you read exactly how much has been dispensed, which is what a titration needs. A burette is read before and after, and the difference is the volume used.

What is a desiccator used for?

Keeping something dry. It is a sealed vessel containing a drying agent, used to cool a heated sample without it absorbing moisture from the air, which would otherwise change its mass before you weigh it.

Why should glassware be rinsed with the solution rather than water?

Because a film of water left inside dilutes the solution you add next by an unknown amount. Rinsing a burette or pipette with the solution it will contain removes that error, and it matters most in quantitative work like titrations.