Laboratory terms

Semimicro

scale between the macro and micro

Macro

Large scale

Micro

Small scale

Reaction

a substance used to bring about a reaction

Precipitate

any insoluble substance produced in a solution

Residue

that portion of a solid remaining after partial solution by a reagent

Reagent

a substance used to bring out a reaction

Clear solution

one that is not turbid or cloudy

colorless solution

one that is not colored. Do not use “clear“ to mean “colorless“

Filtration and centrifugation

methods for separating a solid from a liquid in which it is suspended

test

a laboratory operation designed to show the presence or absence of some substances, usually some ionic species

positive test

may indicate:

1. formation of a precipitate of distinct color or texture

2. dissolution of a precipitate

3. appearance or disappearance of a color in a solution or in a flame

4. evolution of a gas

5. development of characteristic odor

Sensitive test

positive test given by the smallest amount or concentration of a substance

specific test

test given by one and only one substance

confirmatory test

when a test is nonspecific in character, additional evidence is frequently sought as final proof of the presence of the ion

blank

consists of all the reagents present and otherwise treated exactly as the test. it does not contain the ion or substance tested.

control

a known sample with the ion under consideration has already been added

test solutions

contains the ion or substance for which tests are made, that is, substances that may occur in the unknown. Tests solutions are used in the preliminary experiments as a source of the ions being studied.