Illustrated Guide to Home Chemistry Experiments

48 DIY Science: Illustrated Guide to Home Chemistry Experiments

high purity that were listed in earlier editions of the USP, NF, or

FCC compendia, but are no longer listed in the current editions.

Either of these grades of chemicals is suitable for general use

in home labs.

practical grade or chemically pure (Cp) grade
Practical grade and chemically pure grade (CP grade)
chemicals are of purity suitable for use in syntheses and
other general applications, but are a step down in purity from
laboratory or purified grade, and are not intended for analytical
work. Either of these grades is acceptable for general use in
home labs when purer grades are unavailable or unaffordable.

Technical grade
Technical grade chemicals are generally supplied in bulk
quantities and are suitable for general industrial use, but
should be used only as a last resort in a home chemistry lab.

Ungraded
Ungraded chemicals are produced for household, agricultural,
and other uses where high purity is unimportant. The actual
purity of ungraded chemicals can range from very poor to
surprisingly good. To a large extent, the actual purity of these
chemicals depends on the production process used to make
them. For example, hydrochloric acid sold in hardware stores
as “muriatic acid” for cleaning concrete is produced by reacting
hydrogen and chlorine gases and dissolving the resulting

hydrogen chloride gas in water, which may be ordinary tap

water but is often distilled or deionized. Because there are

few opportunities in the production process for the product to

be contaminated, the muriatic acid you can buy in hardware

stores is often of purity comparable to laboratory grade. Of

course, by definition there are no guarantees of purity with

ungraded chemicals.

Industry-specific grades

Many industries have industry-specific grading systems

for chemicals, but the only one you’re likely to encounter is

photo grade. A photo grade chemical is one that contains

only impurities that do not interfere with the intended use

of the chemical in photographic processing. Photo grade

chemicals may contain other impurities, which may or may not

interfere with other uses. In general, photo grade chemicals are

comparable in purity to laboratory grade or purified grade, and

most are suitable for use in a home chemistry lab.

The best advice is to buy the purest chemicals you can afford,

always keeping an eye on the intended use of those chemicals

and the price differential between grades. If you have to control

costs by buying only some chemicals in high-purity grades, we

recommend that you buy purer grades of frequently used primary

chemicals such as mineral acids, sodium hydroxide, and so on.

Avoid anything less than laboratory/purified grade if you can

possibly do so.

TowRof BE ABEL

It’s up to the manufacturer or supplier to decide how

to label a chemical. The same chemical from different

suppliers may be labeled differently, using none, one, or

multiple hazard-labeling methods. Furthermore, different

suppliers may emphasize different hazards for the same

chemical. For example, if a chemical is both toxic and

flammable, one supplier may emphasize the former

hazard and another supplier the latter hazard.

CHEmICAL RISk fACToRS ANd SAfETy AdvICE

Any chemical can be dangerous, given the right (or wrong) conditions. People have died from

acute water toxicity, which is to say from drinking too much water. Still, some chemicals are

obviously more hazardous than others. Government and industry groups have created various

labeling systems to warn users of the type and degree of danger associated with chemicals

that present greater than normal hazards for storage, handling, and use. The following sections

describe the safety information and hazard labeling systems you’re most likely to encounter.

MTERIALA SAFETY DATA SHEETS (MSDS)

The MSDS (Material Safety Data Sheet) for a chemical presents

pertinent safety information in a structured format that includes

the following categories:

1. Product Identification


2. Composition/Information on Ingredients


3. Hazards Identification


4. First Aid Measures


5. Fire Fighting Measures


6. Accidental Release Measures


7. Handling and Storage