58 DIY Science: Illustrated Guide to Home Chemistry Experiments
sulfate. The much more toxic chromium(VI) cation can
be reduced to chromium(III) with an excess of hydrogen
peroxide and then precipitated as chromium(III) sulfate.
Chromate and dichromate anions can be treated by adding a
stoichiometrically equivalent amount of a soluble lead(II) salt,
such as lead(II) nitrate or lead(II) acetate, which precipitates
the chromium ions as insoluble lead(II) chromate. In any case,
filter the precipitate and dispose of it (including the filter
paper) in a hazardous waste container. The filtrate contains few
chromium ions, and can safely be flushed down the drain.Copper
Soluble copper salts are moderately toxic and moderately
dangerous for the environment. Precipitate copper(I) ions
by adding an excess of potassium iodide to form insoluble
copper(I) iodide. Precipitate copper(II) ions by adding
excess sodium carbonate or sodium hydroxide to form
insoluble copper(II) carbonate or copper(II) hydroxide. Filter,
and dispose of the filtrand and filter paper in a toxic waste
container. The filtrate contains few copper ions, and can safely
be flushed down the drain.
Lead
Soluble lead salts are extremely toxic and dangerous for the
environment. Precipitate lead ions by adding an excess of
sodium carbonate to form insoluble lead carbonate. Filter,
and dispose of the filtrand and filter paper in a toxic waste
container. The filtrate contains few lead ions, and can safely be
flushed down the drain.Silver
Soluble silver salts are toxic and dangerous for the
environment. Precipitate silver ions by adding excess
potassium iodide to form insoluble silver(I) iodide. Filter,
and dispose of the filtrand and filter paper in a toxic waste
container. The filtrate contains few silver ions, and can safely
be flushed down the drain.CHEmICALS USEd IN THIS Book
Any home chemistry lab needs a good selection of chemicals. When I started this book, I had no
real idea what I needed, so I ordered a wide variety of potentially useful chemicals. I knew that
some of those chemicals would end up not being used in any of the lab sessions in the book, and
that I might need more of some chemicals than I originally ordered. So I kept careful track of what
chemicals I used for the various labs and in what quantities.
Table 4-4 lists the chemicals required to complete all of the
laboratory sessions in this book, except those in Chapters 19,
20, 21, and 22. With the exception of a few items that must be
purchased from specialty chemical suppliers, all of the chemicals
are readily available from local sources such as the supermarket,
drugstore, and hardware store. Table 4-5 lists the additional
chemicals needed to complete the laboratory sessions in the final
four chapters.
The storage, risk, and safety information in Tables 4-4 and 4-5 is
neither authoritative nor definitive. For chemicals that list “none”
under R(isk)-phrases and/or S(afety)-phrases, an MSDS for that
chemical explicitly listed the chemical as nonhazardous
and/or not requiring any safety precautions. For chemicals
for which the R-phrases and/or S-phrases column is empty,
no information was available. Note well: the absence of safety
information does not indicate that a chemical is safe, nor does
the absence of safety information indicate that no special safety
measures are required. Always check a current MSDS for every
chemical before you use it.