Illustrated Guide to Home Chemistry Experiments

Chapter 4: Chemicals for the Home Chemistry Lab 47

names for many chemicals are becoming more commonly used,

particularly among younger chemists. For example, while many

older chemists (and some younger ones) use the common

names potassium ferrocyanide and potassium ferricyanide,

many younger chemists (and some older ones) instead use the

corresponding IUPAC names potassium hexacyanoferrate(II) and

potassium hexacyanoferrate(III). Both naming styles are used

interchangeably in this book, because it’s good to be familiar with

both styles.

assigned CAS numbers, with about 50,000 new CAS numbers

added every week. A CAS number comprises three numeric

strings separated by hyphens, the first of up to six numbers,

the second of two numbers, and the third a single check-digit.

CAS numbers are assigned sequentially, and therefore have

no inherent meaning. CAS numbers are used primarily for

searching the literature.

Most chemists use both systematic and common names,
depending on the chemical in question. Many IUPAC names
for well-known compounds are seldom or never used. For
example, not even the most pedantic chemist uses the IUPAC
name dihydrogen oxide for water or the IUPAC name 1,3,7-
trimethyl-1H-purine-2,6(3H,7H)-dione for caffeine. But IUPAC

CHEmICAL GRAdES

Chemical grades define standards of purity and suitability for use for particular purposes. In order

of decreasing purity (roughly), here are the chemical grades that you should be aware of.

pimary standard grade and specialized ultrapure gradesr
Primary standard grade chemicals are analytical reagents
of exceptionally high purity that are specially manufactured
for standardizing volumetric solutions, preparing reference
standards, and running lot analyses to determine the purity
of production runs of other chemicals. Specialized ultrapure
grade chemicals are sold under various brand names by
laboratory chemical producers and are used for specialized
purposes such as spectroscopy and trace metal analyses.
These chemicals are of the highest purity attainable, are
extremely expensive, and are overkill for any home laboratory.

Reagent ACS Grade
Reagent ACS Grade chemicals meet or exceed the current
American Chemical Society standards for purity, and are
the purest chemicals used routinely in laboratories. These
chemicals are sufficiently pure for any but the most
demanding uses.

Reagent grade
Reagent grade chemicals are of very high purity, but have
not been subjected to the exacting testing and certification
standards required for labeling as ACS Grade. Reagent grade or
better chemicals are required for reliable quantitative analyses,
and highly desirable for qualitative analyses.

USp grade, Nf grade, or fCC grade
USP grade (United States Pharmocopeia), NF grade
(National Formulary), or FCC grade (Food Chemical Codex)
chemicals are manufactured in facilities that comply with
current Good Manufacturing Practices (cGMP) standards

BSTTERE I THE ENEmy of Good ENoUGH

Reagent ACS Grade and reagent grade chemicals are ideal

for use in a home lab, but are often much more expensive

than lower-grade chemicals. Not always, though. They

may even cost less. For example, when I was ordering

chemicals for my home lab, I was about to order 100 g of

a particular chemical in laboratory grade for $6.90 when I

noticed that the same vendor was selling

100 g of the same chemical in reagent grade for $5.95.

If the reagent grade chemical costs the same or little

more than a lower grade, buy the reagent grade chemical.

Otherwise, settle for the lower grade, unless you will use

the chemical to perform critical qualitative analysis or

quantitative analysis procedures.

and that meet the requirements of the USP, NF, or FCC,

respectively. These chemicals are usually of a very high degree

of purity, but may contain impurities that are insignificant for

food or pharmaceutical use but may or may not be significant

for qualitative or quantitative analyses and similar laboratory

procedures. All of these grades of chemicals are suitable for

general use in home laboratories.

Laboratory grade or purified grade

Laboratory grade chemicals are equivalent in purity to USP,

NF, and FCC chemicals, but are not certified for pharmaceutical

or food use. Purified grade chemicals are usually chemicals of