CHEM 18.1 - Activity 3

Test tube

Small cylindrical glass container used to hold, mix, or heat small amounts of substances.

Beaker

Cylindrical container with a spout, used for mixing, stirring, and heating liquids.

Erlenmeyer flask

Conical flask used for swirling/mixing solutions and for titrations.

Volumetric flask

Flask calibrated to hold a precise volume, used for preparing solutions of exact concentration.

Pasteur pipet

Simple dropper-style pipet used for transferring small amounts of liquid.

Wash bottle

Squeeze bottle (filled only with distilled water) used to rinse glassware or add small amounts of water.

Wire gauze

Metal screen placed between a heat source and glassware to distribute heat evenly and prevent breakage.

Test tube holder

Tool used to hold a test tube safely, especially while heating.

Thermometer

Instrument used to measure temperature.

Graduated cylinder

Glass cylinder marked with graduations, used to measure liquid volume when extreme accuracy is not required.

Transfer pipet

Pipet used to deliver a definite/precise volume of liquid.

Buret

Graduated glass tube with a stopcock, used for precise, controlled delivery of liquid (e.g., in titrations).

Buret clamp

Clamp used to hold a buret in place on an iron stand.

Iron stand

Vertical support rod/base used to hold other apparatus (rings, clamps) above the lab bench.

Iron clamp

Clamp attached to an iron stand to hold glassware in place.

Iron ring

Ring attached to an iron stand used to support a beaker/flask or a funnel above a heat source.

Evaporating dish

Shallow dish used to evaporate solvent from a solution.

Spatula

Small tool used to scoop or transfer solid chemicals.

Watch glass

Curved glass dish used to hold small samples, cover beakers, or smother small fires.

Funnel

Cone-shaped device used to guide liquids or filter paper for filtration.

Test tube rack

Rack used to hold multiple test tubes upright.

Bunsen burner

Gas burner used as a heat source in the laboratory.

Stirring rod

Glass rod used to stir solutions or guide liquid during pouring.

Crucible tong

Tool used to safely handle hot crucibles or other hot objects.

Top loading balance

Balance used to weigh objects/chemicals to the nearest 0.01 g.

Centrifuge

Device that spins samples at high speed to separate components by density.

Hot plate

Electric heating device used as an alternative to an open flame.

Meniscus

The curved surface of a liquid inside a glass tube; volume is read at the lowest point of the curve, with the eye kept level with it.

Graduated Cylinder (technique)

Used to measure liquid volume when high precision is not required; the cylinder's volume should not exceed ten times the volume being measured.

Pipet (technique)

Delivers a precise volume of liquid; filled using a rubber bulb aspirator, held with the forefinger over the top, and drained with proper tip-touching and draining time to ensure calibrated accuracy.

Buret (technique)

Cylindrical graduated tube with an opening at the end for controlled liquid dispensing (detailed use covered in a later exercise).

Weighing

Process of determining mass using a balance; involves selecting a container, taring, carefully transferring the sample, and recording the stabilized reading.

TARE (button)

Balance function used to zero the display, usually after placing an empty container on the pan.

Pouring of Liquids

Technique of pouring liquid down a glass rod into a receiving vessel to prevent dripping and splashing.

Dispensing Chemicals

Techniques for safely removing liquids or solids from reagent bottles/jars without contaminating them (e.g., pouring on the side opposite the label, using creased paper for solids into test tubes).

Heating in a Test Tube

Holding the test tube with a holder at a slant, moving it back and forth, with the opening pointed away from people.

Heating in a Beaker or Flask

Supporting the vessel 1–2 inches above the burner using an iron ring, with wire gauze between the vessel and the flame to prevent uneven heating and breakage.

Precipitate

An insoluble (or only slightly soluble) solid formed when substances in solution interact.

Decantation

The process of separating a liquid from a dense insoluble solid by simply pouring off the liquid.

Supernatant Liquid

The liquid above a precipitate that is poured off during decantation.

Filtration

The separation of a solid from a liquid by passing the liquid through a membrane (filter paper).

Filtrate

The liquid that passes through the filter membrane during filtration.

Residue (filtration)

The solid left behind on the filter paper after filtration.

Washing (of a precipitate)

Rinsing a precipitate (often by decantation in the original vessel) with a wash liquid, usually distilled water, to remove residual ions from the supernatant.

Evaporation

The process of removing solvent from a solution by heating it (e.g., in an evaporating dish) until it boils gently away.

Residue (evaporation)

The material that remains in the dish after evaporation is complete.

Water Bath

A heating method where a container (e.g., evaporating dish) is heated indirectly by placing it on or over boiling water rather than directly over a flame.