Safe Laboratory Practice

Why this skill matters

Safety precautions are tested on Paper 5 (planning) and Paper 6 (practical skills). A safety mark is available in most planning questions, and mishandling safety in your answer suggests a lack of practical understanding. Examiners want specific, relevant safety points, not generic lists.

Method and technique

Hazard symbols (GHS pictograms)

All hazard symbols use a red diamond border:

Symbol	Meaning	Example substances
Corrosive	Destroys living tissue and metals	Concentrated sulfuric acid, sodium hydroxide
Flammable	Catches fire easily	Ethanol, hexane, hydrogen gas
Toxic	Can cause death or serious illness in small amounts	Chlorine gas, lead compounds
Harmful/Irritant	Can cause minor injury or irritation	Dilute acids, copper sulfate
Oxidising	Provides oxygen, can intensify fire	Potassium manganate(VII), hydrogen peroxide
Environmental hazard	Harmful to aquatic life	Heavy metal compounds

General safety rules

1. Always wear safety glasses when heating, using chemicals, or handling glassware.
2. Never taste chemicals unless specifically instructed (extremely rare at IGCSE level).
3. Never smell chemicals directly. If you need to detect an odour, waft fumes toward your nose by waving your hand over the container opening.
4. Tie back long hair when using a Bunsen burner.
5. Stand when working so you can step back quickly if something spills.
6. Know the location of safety equipment: fire extinguisher, fire blanket, eye wash station, first aid kit.
7. Report all spills, breakages, and injuries to the teacher immediately.

Specific safety precautions by situation

Heating flammable liquids: Use a water bath or electric hotplate, never a naked flame. Flammable vapours can ignite from a Bunsen burner some distance away.

Producing toxic or irritant gases: Work in a fume cupboard. Gases like chlorine, sulfur dioxide, nitrogen dioxide, and ammonia should not be released into the laboratory.

Using corrosive substances: Wear safety glasses and gloves. If concentrated acid is spilled on skin, wash immediately with plenty of water.

Heating liquids in test tubes: Point the tube away from all people. Bumping (sudden boiling) can eject hot liquid.

Cutting or drilling glass tubing: Wrap in a cloth, score gently, snap away from your body. Glass cuts are the most common laboratory injury.

Risk assessment in planning

When writing a method for Paper 5, include a risk assessment:

1. Identify the hazard (what could cause harm)
2. State the risk (who could be harmed and how)
3. State the precaution (how to reduce the risk)

Example: “Concentrated hydrochloric acid is corrosive and could damage skin or eyes. Wear safety glasses and gloves, and use in a fume cupboard due to the irritant fumes.”

Common errors and how to avoid them

Listing irrelevant precautions: Saying “wear a lab coat” for every experiment is generic. State precautions relevant to the specific chemicals and procedures in the experiment.

Missing the fume cupboard: When an experiment produces chlorine, SO2, NO2, or concentrated acid fumes, the fume cupboard is essential. Forgetting it loses a mark.

Confusing harmful and toxic: Harmful substances cause minor irritation. Toxic substances can cause death or serious illness. The precautions differ in severity.

Marking points examiners look for

• Safety glasses/goggles worn (almost always relevant)
• Fume cupboard named for experiments producing toxic/irritant gases
• Water bath specified for heating flammable liquids
• Specific hazard identified by name (not just “it is dangerous”)
• Precaution matched to the specific hazard
• Correct use of terms: corrosive, flammable, toxic, harmful, irritant