1.8.1Unit 1. Structure, Bonding and Introduction to Organic Chemistry
Hazards and Risks — IAL Edexcel Linear (Chemistry) Revision Notes & Topical Questions
5 min read 5 parts Lesson 27 of 36 Unit quiz
Part 1 of 5Hazard Versus Risk
Every practical should begin with an assessment of what could go wrong and how to prevent it.
Hazard
- A hazard is the inherent property of a substance or procedure that could cause harm, such as being corrosive or flammable.
Risk
- Risk is the chance that the hazard will actually cause harm, which depends on how the substance is handled and in what amount.
Water example
- Cold water has almost no hazards, but boiling it on a tripod has risks of scalding from steam and spilled liquid.
Acid example
- Dilute hydrochloric acid is a corrosive hazard, and the risk to the eyes is reduced by wearing eye protection.
Part 2 of 5Hazard Symbols
Hazard Symbols
Corrosive
- Substances such as concentrated acids and alkalis that destroy living tissue and metals on contact.
Flammable
- Liquids and gases such as ethanol and propane that catch fire easily, so naked flames must be kept away.
Toxic
- Substances such as many heavy metal compounds that can cause serious harm or death if swallowed, inhaled or absorbed.
Oxidising
- Substances such as potassium manganate(VII) that can make other materials burn more fiercely.
Irritant or harmful
- The exclamation-mark symbol warns of skin or eye irritation and of less severe toxicity.
Environmental
- Substances that damage aquatic life must be disposed of carefully and never poured down the sink.
Part 3 of 5Carrying Out a Risk Assessment
1
List every chemical and piece of apparatus and identify the hazards using safety data sheets or labels.
2
Decide how likely each hazard is to cause harm and how serious the harm could be.
3
Choose control measures such as eye protection, gloves, a fume cupboard or a smaller quantity of reagent.
4
Plan for emergencies, including what to do about spills, burns or inhalation.
5
Record how waste will be disposed of and review the assessment if the method changes.
Part 4 of 5Typical Control Measures
Typical Control Measures
Flammable liquids
- Heat them with a water bath or electric heater rather than a naked flame, and keep containers closed.
Toxic gases
- Work in a fume cupboard so that vapours such as chlorine or bromine are removed and not breathed in.
Corrosive liquids
- Use dilute solutions where possible and wear goggles, and wash any spill off skin with plenty of cold water.
Heating glassware
- Never heat a closed system, point test tubes away from people and use a clamp or holder to avoid burns.
Part 5 of 5Exam Checklist & Tips
1.8.1 – Key Points for the Exam
- Hazard A property of a substance or process that has the potential to cause harm.
- Risk The likelihood and severity of harm from a hazard in a particular situation.
- Risk assessment A planned review of hazards, risks and control measures before an experiment.
- Corrosive Able to cause chemical damage to skin, eyes or metals on contact.
- Control measure An action taken to lower the risk, such as using a fume cupboard.
Common Mistakes
- Using the words hazard and risk as if they mean the same thing.
- Saying that eye protection removes the hazard; it only reduces the risk.
- Suggesting a naked flame for heating flammable liquids such as ethanol.
- Writing precautions that do not match the hazard, such as gloves for a toxic gas.
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