Theory — Foundations of Laboratory Practice
A laboratory is a workspace where chemistry happens — but only safely and reliably when the people in it know what they are doing. Every successful experiment starts with three pieces of knowledge: what equipment to use, how to use it correctly, and how to keep yourself and others safe. This lab introduces all three. By the end of it, you will recognise common glassware on sight, know which piece is right for a given task, understand the GHS hazard symbols you will see on every chemical bottle, and have a mental playbook for the most common laboratory emergencies.
1. Common laboratory glassware
Glassware is grouped by purpose. Some pieces are designed for volumetric measurement (high accuracy), others for approximate measurement (rough volumes), others for reaction or transfer (no measurement intended). Using the wrong category gives the wrong answer:
| Item | Category | Typical use | Accuracy |
|---|---|---|---|
| Volumetric flask | Volumetric (TC) | Preparing standard solutions to a precise volume | ±0.05–0.20 mL (Class A) |
| Pipette (volumetric / bulb) | Volumetric (TD) | Delivering a single fixed volume precisely | ±0.01–0.06 mL (Class A) |
| Burette | Volumetric (TD) | Variable volume delivery for titrations | ±0.02–0.10 mL (Class A) |
| Graduated cylinder | Approximate | Measuring volumes when ±1% precision is enough | ±0.5–5 mL depending on size |
| Beaker | Approximate / reaction | Stirring, mixing, heating; markings are estimates only | ±5% (graduations indicative only) |
| Erlenmeyer flask | Reaction / titration | Holding the analyte during titration; swirling | Volume marks indicative only |
| Round-bottom flask | Reaction | Reflux, distillation; even heating in heating mantle | Not for measurement |
| Pasteur pipette | Transfer | Transferring small volumes; not for measurement | Not graduated |
| Watch glass | Cover / weighing | Covering a beaker; weighing small solid samples | Not for measurement |
| Büchner funnel + flask | Filtration | Vacuum filtration of crystalline solids | Functional, not volumetric |
TC vs TD: a critical distinction. Volumetric flasks are marked "TC" (To Contain) — they hold the stated volume when filled to the line. Pipettes and burettes are marked "TD" (To Deliver) — the stated volume is what comes OUT of them, accounting for the small film that stays on the glass. Never use a TC piece as if it were TD or vice-versa.
2. The GHS hazard symbols
Every chemical container in a modern laboratory carries one or more GHS pictograms (a globally harmonised system since 2015). Each diamond-shaped symbol with a red border conveys a class of hazard at a glance:
Flame
Flammable. Liquid, vapour, or solid that catches fire easily. Examples: ethanol, diethyl ether, acetone. Keep away from open flames, hot plates, and sparks.
Skull and crossbones
Acute toxicity. Can cause death or serious harm at low doses. Examples: NaCN, NaN₃, OsO₄. Fume hood; double gloves; never pipette by mouth.
Corrosion
Corrosive. Causes severe skin/eye burns or attacks metals. Examples: conc. H₂SO₄, NaOH, HF. PPE mandatory; rinse 15 minutes if contacted.
Health hazard
Long-term health risk. Carcinogen, mutagen, reproductive toxin, respiratory sensitizer. Examples: benzene, chloroform, formaldehyde. Fume hood mandatory.
Exclamation mark
Irritant or harmful. Less severe than acute toxic. Eye/skin irritant or low-level harmful. Standard PPE; rinse if contacted.
Exploding bomb
Explosive or self-reactive. Examples: dry picric acid, peroxide-formers like old ether. Special storage; do not let them dry out.
Three more pictograms exist (oxidiser — flame over circle; gas cylinder — gases under pressure; environment — dead fish/tree, aquatic toxicity), but the six above cover most laboratory chemicals you will meet. Reading the pictograms takes about a second; doing it before opening a bottle takes about a second longer than not doing it. Always do it.
3. PPE: personal protective equipment
The three pieces of PPE that should be on you before you touch a chemical:
- Splash goggles — actual goggles that seal around the eyes, not safety glasses. Most lab eye injuries are from splashes coming from the side; goggles block them.
- Lab coat — a long-sleeved coat that covers torso and arms. Closed front. Removable in case of splash; never wear back to a public space (it's contaminated).
- Gloves — nitrile is the default. Latex gives less chemical resistance; vinyl is often inadequate. Replace gloves immediately if contaminated. Do not handle door knobs or phones with contaminated gloves.
Additional PPE for specific cases: fume hood for volatile or toxic chemicals; face shield for high-risk operations (acid dilution, large quench); respirator for confirmed inhalation hazards (rare in undergraduate labs); insulated gloves for very hot or cryogenic work.
4. Fundamental laboratory techniques
The eight techniques below recur in nearly every chemistry experiment. Master them, and most synthesis recipes become readable as a sequence of operations rather than a list of unfamiliar verbs.
| Technique | Purpose | Key glassware |
|---|---|---|
| Weighing | Measuring mass of solids; primary standard for stoichiometry | Analytical balance, weighing paper or weighing boat |
| Pipetting | Delivering precise volumes of liquid | Pipette + bulb (never mouth) |
| Filtration (gravity) | Separating solid impurities from a liquid product | Funnel, filter paper, beaker |
| Filtration (vacuum) | Collecting a crystalline solid product, drying it | Büchner funnel, filter flask, vacuum line |
| Recrystallisation | Purifying a solid by dissolving in hot solvent and re-crystallising | Erlenmeyer flask, hot plate, Büchner setup |
| Distillation | Separating liquids by boiling point | Distillation head, condenser, receiver flask, heat source |
| Liquid-liquid extraction | Separating compounds between two immiscible solvents | Separating funnel, two beakers |
| Titration | Determining concentration by adding a standard solution to an endpoint | Burette, Erlenmeyer, indicator |
5. Lab safety procedures and emergency response
Every chemistry laboratory has the same four pieces of emergency equipment. Locate them BEFORE you start any experiment:
Eyewash station
For chemical splash to the eyes. Push the lever, hold the eyes open, rinse for at least 15 minutes. Do not stop early — chemicals continue to be removed throughout. Get medical help.
Safety shower
For larger spills onto skin or clothing. Pull the chain, stand under the shower fully clothed, rinse for at least 15 minutes. Remove contaminated clothing while under water. Call for help.
Fire extinguisher
CO₂ for electrical fires; dry chemical (ABC) for general fires. Use only on small fires you can safely approach. Never use water on a chemical or oil fire — it spreads the fire. Evacuate if larger.
Fire blanket
For clothing fires. Do not run — running fans the flames. Wrap the blanket around the person; smother the flames; have them stop, drop, and roll if needed.
Key principles for accident response:
- Stay calm. Move quickly but do not run. Inform the instructor immediately.
- Skin or eye contact: flood with water for ≥15 minutes. Remove contaminated clothing. Then medical attention.
- Inhalation: move to fresh air. If unwell, call medical help.
- Cuts (especially from broken glass): control bleeding with pressure; medical attention if deep or contaminated.
- Spills: contain first (vermiculite, spill kit), then clean. Notify the instructor for any non-trivial spill.
- Never use water on Na/K, on phosphorus, on burning oil, or on electrical fires.
6. Common processes you will perform repeatedly
Two sequences appear in nearly every synthesis lab and are worth memorising:
2. Transfer to a separating funnel; add organic solvent and wash phase
3. Separate the organic phase; back-extract the aqueous phase if needed
4. Wash organic combined extract with brine to remove most of the water
5. Dry over anhydrous Na₂SO₄ or MgSO₄
6. Filter the drying agent away, concentrate by rotary evaporation
Result: dry organic crude product ready for purification
2. Filter hot if there is insoluble matter (gravity filtration through fluted filter paper)
3. Cool slowly to crystallise pure product
4. Filter crystals (Büchner funnel, vacuum)
5. Wash crystals with cold solvent, suck dry
6. Dry overnight in air or in a vacuum desiccator
Result: pure crystalline product, characterised by m.p. and spectroscopy
You will use both sequences dozens of times during the year. Each step of each sequence has a specific purpose and a specific pitfall. The simulation in this lab walks you through both, with the chance to make (and then correct) the most common student mistakes.
Instructions
This lab's Simulation section has four parts. Complete them in order — together they cover every essential lab skill you'll need before starting any chemistry-specific module.
Why do this lab first? Every other lab in the course assumes you can identify glassware on sight, know which PPE to wear, recognise GHS pictograms, and respond correctly to incidents. Without these skills, the chemistry-specific labs become harder to follow and less safe. Spend the time here so the rest of the course goes smoothly.
Simulation
Four interactive parts — work through them in order.
Identify each piece of glassware. For each: (a) name, (b) primary use, (c) accuracy category.
For each laboratory scenario, choose the correct safety response.
Eight fundamental laboratory techniques. For each, answer two questions: (a) when to use it, (b) the most common mistake.
Round 1 — Identify the GHS hazard pictogram
Six pictograms with their typical meanings. Match each pictogram to the hazard class it represents.
Round 2 — SDS comprehension
Eight questions about reading and interpreting Safety Data Sheets in everyday lab use.
Team Questions
Discuss with your team. These cover the foundational skills tested across all four sections.
Example Lab Notebook Entry
A first lab does not produce experimental data, but it does produce a record. Use this format for your notebook entry — it builds the habit you will need for every chemistry lab afterwards.
Lab Skills & Safety — Notebook Entry
Submitted by: [Student Name]
Course: Foundation Lab · Section: 101-A · Date: April 24, 2026
Objective
To recognise common laboratory glassware on sight, identify the GHS hazard pictograms, demonstrate knowledge of the correct safety responses to common laboratory incidents, and describe the purpose and procedure of fundamental laboratory techniques (filtration, recrystallisation, distillation, extraction, titration, weighing, pipetting, drying).
Learning outcomes covered
Glassware identification (Section I); GHS hazard symbol recognition (Section IV, Round 1); SDS reading and interpretation (Section IV, Round 2); emergency response procedures (Section II); fundamental laboratory techniques (Section III).
Glassware reference (Section I results)
| Item | Category | Primary use |
|---|---|---|
| Volumetric flask (250 mL) | Volumetric (TC) | Preparing standard solutions to a precise volume |
| Volumetric pipette (25 mL) | Volumetric (TD) | Delivering a single fixed volume precisely |
| Burette (50 mL) | Volumetric (TD) | Variable volume delivery for titrations |
| Graduated cylinder (100 mL) | Approximate | Measuring volume when ±1% precision is enough |
| Beaker (250 mL) | Approximate / reaction | Holding, stirring, mixing — markings indicative only |
| Erlenmeyer flask (250 mL) | Reaction / titration | Holding the analyte during titration; allows swirling |
| Round-bottom flask (250 mL) | Reaction | Reflux, distillation; even heating in heating mantle |
| Pasteur pipette | Transfer | Transferring small volumes; not for measurement |
| Watch glass | Cover / weighing | Covering a beaker; weighing solid samples |
| Büchner funnel + flask | Filtration | Vacuum filtration of crystalline solids |
GHS pictograms — quick reference
| Pictogram | Hazard class | Example chemicals |
|---|---|---|
| Flame | Flammable | Ethanol, acetone, diethyl ether |
| Skull and crossbones | Acute toxicity | NaCN, NaN₃, OsO₄ |
| Corrosion | Corrosive (skin/eyes/metals) | Conc. H₂SO₄, NaOH, HF |
| Health hazard | Carcinogen, mutagen, reproductive toxin | Benzene, chloroform, formaldehyde |
| Exclamation mark | Irritant; less severe than acute toxic | Most laboratory solvents at low concentration |
| Exploding bomb | Explosive or self-reactive | Dry picric acid, old peroxide-formers |
Emergency response — summary table
| Incident | First action | Equipment |
|---|---|---|
| Chemical splash to eyes | Eyewash for ≥15 minutes | Eyewash station |
| Large chemical splash on body | Safety shower for ≥15 minutes | Safety shower |
| Small fire (solvent in beaker) | Cover with watch glass to smother | Watch glass / fire blanket |
| Larger fire | Evacuate; alert others; activate alarm | Fire extinguisher (CO₂ or ABC) |
| Clothing fire | STOP, DROP, ROLL or fire blanket | Fire blanket |
| Cut from broken glass | Apply pressure with clean cloth | First-aid kit |
| Small spill (non-volatile) | Contain with absorbent; clean up | Spill kit |
| Inhalation of fumes | Move to fresh air immediately | — |
Discussion
The first laboratory experience taught me that nearly every successful chemistry experiment depends on three preconditions: knowing what equipment to use, recognising the chemicals involved, and being prepared to respond to anything that goes wrong. The clear distinction between volumetric glassware (precise; for standard solutions) and approximate glassware (e.g., beakers; for stirring) was new to me — I learned that using a beaker to measure 25.0 mL of a solution would introduce an unacceptable ±5% error compared to a volumetric pipette's ±0.06 mL.
The GHS pictogram system condenses complex hazard information into instantly recognisable diamond-shaped icons. The most useful insight was that the same chemical can carry several pictograms simultaneously: chloroform, for example, is both an "exclamation mark" (irritant) and a "health hazard" (carcinogen) and is volatile enough that it should be handled in a fume hood at all times. Concentrated sulfuric acid carries the corrosion pictogram (severe burns) and is a strong oxidiser/dehydrant. Reading the pictograms BEFORE picking up a bottle is the single fastest safety habit one can build.
The most counter-intuitive piece of safety advice I learned was: in cases of skin contact with strong acid or base, do NOT try to neutralise the chemical; flood the affected area with water for at least 15 minutes. The exotherm of neutralisation can make the burn worse than the original chemical contact. The same applies to spills — water dilution is almost always the right response, never neutralisation.
Conclusion
I have demonstrated competence in (1) identifying common laboratory glassware and selecting the appropriate piece for a given task; (2) reading GHS hazard pictograms and SDS extracts; (3) describing the correct response to common laboratory emergencies; (4) explaining the purpose and procedure of eight fundamental laboratory techniques. I now feel prepared to begin the chemistry-specific modules of the course, with the safety habits and equipment knowledge to do so productively.
References
1. Furr, A. K. (Ed.). CRC Handbook of Laboratory Safety, 5th ed., CRC Press, 2000.
2. United Nations. Globally Harmonised System of Classification and Labelling of Chemicals (GHS), 9th rev. ed., UN, 2021.
3. ASTM E287-22. Standard Specification for Laboratory Glass Graduated Burettes.
4. Sigma-Aldrich Safety Data Sheet templates, accessed online March 2026.
Practice Questions
Test your understanding. Try each one before peeking at the hint.