Safety in the Laboratory Chemistry Tutorial

Key Concepts

Safety in the Laboratory is the reponsibility of everyone in the laboratory.
This includes teachers, students, lab technicians (assistants) and visitors to the lab.

Before undertaking any practical work (experiments) in the laboratory, you should ask yourself the following 5 questions:

Question 1: Do I know the safety rules for working in this laboratory?

Question 2: Do I know where the safety equipment is located in this laboratory?

Question 3: What are the possible hazards (dangers) during this experiment?

Question 4: What are the possible consequences (risks) of these hazards?

Question 5: For this experiment, is it possible to:

(i) eliminate the risk?

Is it necessary to use this chemical?

Is it necessary to undertake this dangerous process?

(ii) substitute a safer alternative?

Can you use a different, less hazardous chemical?

Can you use a different, less hazardous process?

(iii) guard against the risk?

Will using particular safety equipment minimise the hazard?

If you are performing an experiment using the materials and method provided by your teacher, you will need to concentrate on thinking about how to guard against the possible risks.

If you are designing and carrying out your own experiments, you will need to confer with your teacher during the design process in order to determine whether the potential risks can be eliminated, substituted, and/or guarded against.

Download a free Student Safety Agreement.

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Safety Rules

Different laboratories will have different safety rules depending on the type of experiments conducted in them.

Below is a list of general rules that would apply to most chemistry laboratories.

Safety Equipment

Different laboratories will have different safety equipment depending on the type of experiments conducted in them.

You should not handle any safety equipment unless you have been given instructions about the correct use of the equipment.
Incorrect use of safety equipment can be dangerous!

Your teacher should be told immediately about any dangerous situation or emergency that arises during your work in the lab.

If you have not been given a sketch of the layout of the laboratory which includes the location of the safety equipment and emergency exits, you should draw a sketch yourself and include the locations of each of the following:

Personal Protective Equipment (PPE)

Safety equipment designed to protect a single person (just you) from injury is known as personal protective equipment (abbreviated as PPE). Personal protective equipment includes wearing the appropriate clothing, shoes and accessories.

The personal protective equipment you should use in the chemistry laboratory is given below:

Possible Hazards: Signage

Some hazards are general hazards, such as skidding on a wet floor, or tripping over your own feet when running. These hazards are present everywhere. It is important to be aware that these hazards are even more dangerous in the chemistry laboratory and you should take care to minimise the risk of injury due to these general hazards.

For example, electrical equipment, found in your home and in the laboratory, can be dangerous. To ensure you use electrical equipment safely, you should:

• keep electrical equipment away from water sources.
• prevent electrical cords being coiled as the build up of heat may cause a fire or damage the external (protective) casing.
• position electrical cords so that they do not pose a trip hazard.
• not use any equipment, power socket or power board which has a "Do Not Use" sign or label on it.

In the Chemistry lab there are other hazards, chemical hazards, that you may not find in other places, or, which become even more dangerous, even life-threatening in the context of the lab.

Hazardous chemical substances are labelled so that we can

• quickly identify the kind of risk or hazard associated with the substance
• take precautions to protect ourselves, and others, from the risk

The label on a container of a chemical reagent contains information about the risks or hazards associated with its use in the form of a

• pictogram (a picture representing the risk or hazard)⁽¹⁾
• word (to describe the risk or hazard)

The pictogram and/or the word on the label of a hazardous substance summarises the risk involved in using the substance.

Suitable precautions should then be taken to minimize the risk when working with the substance.

The table below summarises the meaning of common pictograms and gives the typical safety precautions required to work with the substance.

Pictogram Hazard	Substance is	Risk/hazard is	Examples	Typical Safety Precautions
GHS01:Explosive	⚛ unstable explosives ⚛ self reactive substances ⚛ some organic peroxides	Substance will react quickly to produce huge amounts of gas in an explosion.	Alkali metals reacting with water (lithium sodium, potassium, rubidium, caesium) Ammonium dichromate Gunpowder 2,4,6-Trinitrotoluene (TNT) Nitroglycerin (dynamite, gelignite) Picric acid	Use only small amounts of explosive materials. Perform any experiment behind an explosion-proof barrier (closed fume hood or fume cupboard may be adequate in some cases). Wear eye protection (glasses or goggles). Wear suitable clothing, eg lab coat, closed in shoes, and gloves, to protect your skin.
Pictogram Hazard	Substance is	Risk/hazard is	Examples	Typical Safety Precautions
GHS02:Flammable	⚛ flammable solid ⚛ flammable liquid ⚛ flammable gas ⚛ some organic peroxides ⚛ self-heating substances and mixtures	Substance will burn in the presence of oxygen and a heat source.	Methane gas Liquid alcohols like ethanol Acetone (propanone) Ethyl acetate (ethyl ethanoate) Solid phosphorus	Keep the substance away from naked flames, for example, use a water bath, an oil bath, a heating mantle or hot plate to heat the substance safely.
Pictogram Hazard	Substance is	Risk/hazard is	Examples	Typical Safety Precautions
GHS03:Oxidising	⚛ oxidising solid ⚛ oxidising liquid ⚛ oxidising gas	Can cause fires if they make contact with any combustible material.	Solid potassium dichromate Solid potassium permanganate Concentrated nitric acid Concentrated hydrogen peroxide	Keep away from combustible materials. Perform oxidising experiments in fume cupboard.
Pictogram Hazard	Substance is	Risk/hazard is	Examples	Typical Safety Precautions
GHS04:Compressed Gas	⚛ compressed gas ⚛ liquefied gas ⚛ dissolved gas	Pressurized containers may burst if heated. Refrigerated gases may cause cryogenic burns or injury.	Liquid nitrogen Liquefied petroleum gas (LPG)	General: do not heat cylinder! For liquefied gases like liquid nitrogen: Wear insulating gloves to prevent contact with skin on hands. Wear long sleeved lab coat to protect arms and torso. Wear long pants to prevent contact with skin on legs. Wear enclosed shoes to prevent contact with skin on feet. Wear eye protection (safety glasses or goggles) to prevent contact with eyes.
Pictogram Hazard	Substance is	Risk/hazard is	Examples	Typical Safety Precautions
GHS05:Corrosive	⚛ corrosive to metals ⚛ corrosive to skin ⚛ damaging to eyes	Substance will eat away at your skin and flesh.	Acids (eg hydrochloric acid) Alkalis (eg sodium hydroxide) Some gases (eg chlorine, ammonia) Batteries containing acid.	Wear gloves to prevent skin contact with the substance through your hands. Wear a long-sleeved lab coat to protect your arms and torso. Wear eye protection (glasses or goggles) to prevent substance entering your eyes. Wear closed in shoes to protect the skin of your feet.
Pictogram Hazard	Substance is	Risk/hazard is	Examples	Typical Safety Precautions
GHS06:Toxic	⚛ acutely toxic (oral, dermal, inhalation)	Substance will cause sickness or death if it enters your body.	Cyanides Lead acetate Arsenic compounds Pesticides	Wear gloves, lab coat and closed in shoes to prevent the substance being absorbed through your skin. Use a fume hood (fume cupboard) to prevent breathing any toxic fumes (gases).
Pictogram Hazard	Substance is	Risk/hazard is	Examples	Typical Safety Precautions
GHS07:Harmful	⚛ skin irritant ⚛ eye irritant ⚛ skin sensitization ⚛ respiratory tract irritant ⚛ narcotic effect	Substance is an irritant, can cause skin to itch, eyes to water, coughing, etc	Solid copper sulfate (skin irritant) Styrene (phenylethene) (produces an irritating vapour)	Protect skin using gloves, lab coats and covered shoes. If the irritant is a vapour, perform experiments in fume cupboard.
Pictogram Hazard	Substance is	Risk/hazard is	Examples	Typical Safety Precautions
GHS08:Health Hazard	damaging to genetic material : ⚛ mutagens ⚛ carcinogens ⚛ reproductive toxicity ⚛ respiratory sensitisers ⚛ aspiriaction hazard	(i) Substance contains a virus or bacteria that can cause you serious health problems, even death.	Vaccines Hepatitis	Wear suitable clothing such as lab coat, closed in shoes, eye protection (glasses or goggles), gloves, to prevent contact through your skin. Use a fume hood or fume cupboard to prevent breathing in the hazardous material.
		(ii) Substance gives off radiation which can destroy your cells, cause burns, and could lead to cancer.	Uranium oxide Radiopharmaceuticals used to treat cancer	Any radioactive substance you will use in School will come in special packaging. Do not remove a radioactive substance from its packaging. Radioactive sources should be handled with tongs or forceps and kept at least 30 cm from any person. Minimize the length of time you are exposed to the radiation by keeping the radioactive source in a lead lined container when you are not using it.
Pictogram Hazard	Substance is	Risk/hazard is	Examples	Typical Safety Precautions
GHS09:Environmental Hazard	⚛ an actue or chronic hazard to aquatic environments	Damages things living in water in the short-term and/or in the long-term.	Heavy metals such as mercury and lead.	Put environment-damaging waste into a suitable storage vessel (often a labelled winchester bottle) for appropriate disposal at a later date.

Possible Hazards: Glassware

You will be handling a lot of glassware during your chemistry course. Minor accidents, such as cuts, can be avoided if you are observant.

If any glass is broken in the laboratory, DO NOT pick up the pieces with your bare hands, use a broom to sweep the glass fragments up into a pan, then empty the pan into the glass bin.
DO NOT place glass in the bin used for general waste.

Carefully examine glassware for chips or cracks before you use it.
NEVER use cracked or chipped glassware. Dispose of the glassware in the glass bin.
"Star" cracks can be quite small but can rapidly and suddenly expand if the glassware is heated or placed under vacuum. Dispose of the glassware in the glass bin.

Pasteur pipettes or micropipettes are easily broken and can be sharp.
DO NOT leave these on a bench, always store them in a small beaker when you are not using them.

When using fitted glassware, such as ground-glass male-and-female connections, do not use force to insert the "male" into the "female".

To correctly insert a thermometer into an adapter such as is used for distillation:

1. Turn the screw cap to make a wide aperture so that the thermometer can slide in easily.
2. Hold the thermometer close to the "bulb" or "reservoir" NOT at the very end of the thermometer and insert it through the screw cap.
3. When the thermometer is in place, screw the screw cap firmly but without over tightening.

To correctly attach rubber tubes to water-cooled (Liebig) condensers:

1. Grip the condenser so that the "arm" protrudes through your fingers.
2. Gently insert the "arm" into the rubber tubing. DO NOT use force.

If your condenser has plastic connectors:

1. Undo the connectors first.
2. Attach the rubber tubes.
3. Screw the connectors back into place.

To correctly attach a pipette filler to a pipette always hold the pipette close to where the filler will attach and DO NOT force to insert the pipette into the filler.

Worked Example of How to Work Safely in the Lab: Heating a solid

In a typical thermal decomposition experiment, a small amount of calcium carbonate is placed in a test tube and heated in a bunsen burner flame to produce carbon dioxide gas and calcium oxide.

What safety precautions should be taken during this experiment?

Question 1: Do you know the safety rules for working in this laboratory?

Question 2: Do you know where the safety equipment is located in this laboratory?

Question 3: What are the possible hazards?

Question 4: What are the possible consequences of these hazards (the risks)?

Question 5(i): Is it possible to eliminate the risk?

Question 5(ii): Is it possible to substitute for a safer alternative?

Question 5(iii): Is it possible to guard against, that is, to minimise, the risk?