CHEMISTRY-LABORATORY TECHNIQUES AND SAFETY

LABORATORY TECHNIQUES AND SAFETY

A laboratory is a room or building specially designed for conducting various scientific experiments. An appropriate school laboratory has the following features:

• a room with enough space for carrying out scientific experiments;
• a store for keeping laboratory apparatus, chemicals and reagents;
• an office for laboratory technician to sit in and design scientific experiments;
• enough ventilation to let in fresh air and light;
• wide doors and several exits for emergency evacuation in case of an accident; and
• a wide table in front of the laboratory room, fitted with sinks for experiment demonstrations by the teacher or technician.

Rules and safety precautions in a chemistry laboratory

First aid and first aid kit

Basic chemistry laboratory apparatus and their uses

Instruments used for carrying out different experiments in the laboratory are called laboratory apparatus. Laboratory apparatus can be classified according to their uses as:

• apparatus for holding things e.g. test-tube holder, retort stand and clamp, test-tube rack, tongs and tweezers;
• apparatus for taking measurements e.g. thermometer, burette, pipette, measuring cylinder, measuring flask, beam balance, electronic balance, common balance, measuring syringe, beaker and stop watch;
• apparatus for heating substances e.g. boiling tube, pipeclay triangle, crucible and lid, wire gauze, deflagrating (combustion) spoon, Bunsen burner, spirit lamp, tripod stand, evaporating dish, wire gauze and stove;
• apparatus for doing chemical reactions (or testing) e.g. beaker, test tube, dropper, flask, watch glass, gas jar and thistle funnel;
• apparatus for filtering e.g. filter funnel, filter paper and cotton wool;
• apparatus for grinding e.g. mortar and pestle;
• apparatus for storage e.g. reagent bottles and wash bottle;
• apparatus for scooping e.g. spatula; and
• apparatus for safety e.g. goggles and hand gloves.

The Apparatus Used in a Chemistry Laboratory

List the apparatus used in a chemistry laboratory

Some chemistry laboratory apparatus

Chemistry Laboratory Apparatus According to their Uses

Categorize chemistry laboratory apparatus according to their uses

The apparatus can also be classified based on materials they are made of. Most of the apparatus are made of glass. Others are made of metal, plastic or wood. Just a few are made of clay and asbestos.

Table summarizes some common laboratory apparatus and their uses.

Composition and uses of some chemistry laboratory apparatus

	Apparatus	Material	Uses
1.	Test tube	Glass	Holding chemicals or, heating substances
2.	Funnel	Glass or plastic	Leading liquids into containers, and for filtration purposes
3.	Beaker	Glass or plastic	Holding, heating, and mixing liquids
4.	Flask	Glass	Holding, heating, and titrations
5.	Retort stand	Metal (iron)	Holding apparatus during heating
6.	Tripod stand	Metal (iron)	Holding apparatus during experiments
7.	Gas jar	Glass	Gas collection
8.	Wash bottle	Plastic	Washing
9	Crucible	Ceramic or non-reactive metal	Heating
10	Test tube holder	Metal and plastic or wood	Holding test tubes while heating
11.	Weighing balance	Metal and plastic	Measuring weight (or mass)
12.	Spatula	Metal	Scooping small quantities of powder or crystalline chemicals
13.	Condenser	Glass	Cooling hot liquids
14.	Pipette	Glass	Accurate measurement of specific volumes of liquids for titrations
15.	Burette	Glass	Titrations
16.	Trough	Glass	Assists in gas collection
17.	Tongs	Metal	Picking and holding hot substances and apparatus
18.	Measuring jar	Glass	Measuring volumes of liquids
19.	Thistle funnel	Glass	Leading liquids into containers and apparatus
20.	Dropper	Glass and rubber	Dropping indicators into reagents
21.	Mortar and pestle	Clay	Crushing or grinding substances
22.	Wire gauze	Metal	Even distribution of heat during heating
23.	Spring balance	Metal	Measuring weight
24.	Distillation flask	Glass	Distillation
25.	Combustion spoon	Metal	Burning powder in jars
26.	Thermometer	Glass and liquid metal	Measuring temperature
27.	Delivery tube	Glass	Allowing gases pass through
28.	Bunsen burner	Metal	Heating substances
29.	Separating funnel	Glass	Separation of immiscible liquid mixtures
30.	Measuring cylinder	Glass or plastic	Measuring volumes of liquids
31.	Measuring syringe	Plastic	Sucking in and measuring specific volumes of liquids
32.	Stopwatch	Plastic or glass and metal	Accurate measurement of time
33.	Watch glass	Glass	Used as a surface to evaporate some liquids, to hold substances being weighed or observed, or as a cover for a beaker
34.	Boiling tube	Glass	Is a large test tube used to heat substances requiring strong heating, or when the sample is too large for a test tube
35.	Evaporating dish	Ceramic	Heating and evaporating liquids and solutions
36.	Filter paper	Paper	Filtration
37.	Test tube rack	Wood or plastic	Placing test tubes
38.	Reagent bottle	Glass	Storing different chemicals
39.	Wash bottle	Plastic	Storing distilled water
40.	Safety goggles	Glass	Protecting eyes from chemical spills, strong light and harmful vapours
41.	Bell jar	Glass	Keeping gases, moisture, air, etc. or creating vacuums

Common Chemistry Laboratory Apparatus

Use common chemistry laboratory apparatus

Common laboratory apparatus

Activity 1

Your teacher will guide you how to measure the volume of liquids using the other apparatuses.

Aim: To measure volume of liquids using different apparatus

Materials: pipettes, burettes, measuring cylinders, water, beakers.

Procedure

1. Pour some water into a graduated measuring cylinder with a capacity of 100 cm³. Add the water, one drop at time, up to a 25-cm³ mark.
2. While adding water, position yourself at eye-level with the mark on the cylinder. This will enable you to obtain the most accurate measurement. To simplify the work of reading the level of the water, you may use coloured water.
3. Select a volumetric flask measuring 50 cm³. Pour the water into the flask until it reaches the mark on the flask’s neck.
4. Position yourself at eye-level with the mark. You will obtain the most accurate reading when the mark appears straight rather than elliptical. To obtain this, put a flask on a flat table.
5. Add water one drop at a time. Do so until the bottom of the curved surface of the water exactly matches the mark on the flask.

Activity 1.2

Aim: To measure the masses of solid substances

Materials: chemical, electronic or spring balance, watch glasses, various substances such as sand, sugar, salt, flour, stones, fruits.

Procedure

1. Put an empty watch glass on the weighing balance. Note down its mass. Record this as mass M₁.
2. Place the various items you have on the watch glass, one item at a time. Note down the mass. Record this as M₂.

Note: to obtain the mass of an object, we subtract the mass of an empty watch glass from the mass of the watch glass and the substance. That is, M₂ - M₁.

For example

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