Laboratory Safety and Apparatus
Senior 1 · Chemistry
Laboratory Safety and Apparatus
Lesson 2 of 5
22 min
Read this account of a practical lesson. Six things went wrong. How many can you find before you read on?
Ishimwe arrived late, dropped his bag in the gangway and started the experiment before the teacher had finished explaining. His long sleeves hung loose. He filled a test tube almost to the top with dilute acid and heated it in the flame, holding it upright with his fingers and looking down into it to see it boil. When the liquid spat, he wiped his eye with his hand and carried on. At the end he tipped the leftover liquid into the sink with his biscuit still in his other hand.
Worked example
Problem. List the unsafe actions in Ishimwe's lesson and give the rule each one breaks.
Solution.
| Unsafe action | Rule broken |
|---|---|
| Bag in the gangway | keep bags and stools out of walkways, so no one trips |
| Started before the instructions ended | never start until you have heard all the instructions |
| Loose sleeves, no eye protection | wear a buttoned lab coat and goggles; tie back long hair and loose clothing |
| Tube nearly full, upright, held with fingers, looked into | a third full at most, tilted, in a holder, mouth pointing away |
| Rubbed his eye and carried on | rinse the eye at once with running water and tell the teacher |
| Eating in the laboratory; tipping waste without asking | never eat or drink in the laboratory; dispose of chemicals as the teacher directs |
Answer: six unsafe actions, each of which could have caused a burn, an eye injury or poisoning.
Definition
Hazard: anything that could cause harm, such as a flame, a corrosive acid, hot glass or a wet floor.
Definition
Risk: how likely it is that a hazard will actually cause harm, and how bad the harm would be. Good practice lowers the risk even when the hazard stays. Example: an acid is a hazard; wearing goggles lowers the risk to your eyes.
Definition
Personal protective equipment (PPE): clothing and equipment worn to protect you: a laboratory coat, safety goggles, and gloves when handling corrosive substances.
Table 2.1: Laboratory rules
| Rule | Reason |
|---|---|
| Enter the laboratory only when a teacher is present. | someone trained must be there if an accident happens |
| Wear goggles and a buttoned lab coat; tie back long hair. | eyes are easily damaged; hair and loose clothing can catch fire |
| Never eat, drink or taste anything in the laboratory. | food can pick up poisonous chemicals from benches and hands |
| Read the label twice before you use a chemical. | using the wrong bottle is a common cause of accidents |
| Never smell a chemical directly: waft it (Figure 2.2). | a strong gas can burn the inside of your nose and lungs |
| Point a heated test tube away from everyone (Figure 2.1). | boiling liquid can shoot out of the mouth of the tube |
| Never return unused chemicals to the stock bottle. | they may be contaminated and spoil the whole bottle |
| Clean up spills and report breakages at once. | spilled chemicals and broken glass injure the next person |
| Wash your hands with soap before you leave. | traces of chemicals on your hands can reach your mouth |
Figure 2.1: Heating a liquid in a test tube. A shows the safe method; B shows four mistakes.
Figure 2.2: Wafting. Only a little vapour reaches your nose, so a strong gas cannot hurt you.
Warning
Diluting an acid. Always add the acid to the water, slowly and with stirring, never water to acid. Mixing concentrated acid with water gives out a lot of heat. If water is poured onto the acid, the first drops boil at once and can spray acid out of the container. A memory line: "Add acid to water, as you oughta."
Table 2.2: First aid in the laboratory
| Accident | What to do at once |
|---|---|
| Burn from a flame or hot glass | cool the burn under cold running water for at least 10 minutes; tell the teacher |
| Chemical in the eye | rinse the open eye with running water at the eye-wash station for at least 10 minutes; tell the teacher |
| Chemical on the skin | wash with plenty of running water; remove splashed clothing |
| Chemical swallowed | rinse the mouth with water, do not make yourself vomit, tell the teacher at once and show the label |
| Cut from broken glass | tell the teacher; do not pick up the glass with your fingers; press a clean dressing on the cut |
| Gas smell or leak | turn off the gas taps, open the windows, no flames; tell the teacher |
Worked example
Problem. A class will heat blue copper(II) sulfate crystals in a test tube to drive off their water:
The crystals are harmful if swallowed and irritate the eyes. Write a short risk assessment.
Solution. For each hazard, say what could happen and how to lower the risk.
| Hazard | What could happen | How to lower the risk |
|---|---|---|
| Bunsen flame | burns; hair or sleeves catching fire | tie back hair, roll up sleeves, use a small blue flame |
| Hot test tube | burns if touched; glass may crack | use a holder, let the tube cool on a rack |
| Steam from the crystals | scalding | point the mouth of the tube away from everyone |
| Copper(II) sulfate | harmful if swallowed; irritates eyes | wear goggles, use a spatula, wash hands afterwards |
Answer: with these controls the experiment is safe for a school class.
Tip
Before any experiment ask: What could go wrong? How badly? What will I do to stop it? Those three questions are a risk assessment.
Important
Safety goggles protect you only when they are on your eyes, not on your forehead or around your neck. Keep them on until everyone in the room has finished working, not just you.
Amoeba Sisters: General Lab Safety (6 min). Note each rule they give and compare it with Table 2.1.
Practice
Sources and credits
