Illustrated Guide to Home Chemistry Experiments

30 DIY Science: Illustrated Guide to Home Chemistry Experiments

TABLE 3-3: Recommended supplemental laboratory glassware

Description Qty notes

Bottle, Barnes dropping, 25 mL 12+ Use to store indicator solutions and other solutions that are often

used dropwise.

Bottle, gas-generating 1 Buy or make your own with an Erlenmeyer flask, 1- or 2-hole stopper,

and tubing.

Bottle, gas-washing 1Buy or make your own with an Erlenmeyer flask, 2-hole stopper, and tubing.

Flask, filtering, 250 mL or 500 mL 1Use for faster filtration; requires hand vacuum pump or other vacuum source.

Flask, Florence (flat-bottom), 250 mL1

Better than Erlenmeyer flask for high-temperature distillations and

similar procedures.

Flask, volumetric, 500 mL 1Use for making up larger quantities of bench and stock solutions accurately.

Flask, volumetric, 25 mL 1 Use for making up small quantities of indicators and solutions of expensive

chemicals accurately.

Funnel, Büchner, with stopper 1Use with filtering flask.

Funnel, separatory, 100 mL to 250 mL1Use for separating aqueous and organic phases in extractions or washings.

Funnel, thistle tube 1Useful for adding reactants to a stoppered flask.

LABoRAToRy EqUIpmENT ANd SUppLIES

In addition to glassware, a home chem lab requires a variety of laboratory equipment

and supplies. Some of it you can make yourself, but much of it must be purchased.

BLAEA nC
A good balance is an essential tool for any chemistry lab.
When I built my first home chem lab in the mid-1960s, the
only options were mechanical balances, which were relatively
inaccurate and very expensive. (I ended up building a knife-
edge balance that was usable but never entirely satisfactory.)
Fortunately, there are many accurate, inexpensive electronic
balances available nowadays.

When you choose a balance for your home chemistry lab, pay
close attention to the following important characteristics:

Resolution/Readability
Resolution or readability is the minimum increment of
weight that can be determined by the balance. For example,
a balance may be able to weigh samples to within 0.1 g, 0.01
g (one centigram or cg), 0.001 g (one milligram or mg), or
0.0001 g (100 microgram or μg). All other things being equal,
a balance with higher resolution costs more than one with
lower resolution. The least expensive balances suitable for use
in a home lab cost $60 or so and can weigh samples to within

0.01 g. Balances with resolution of 0.001 g start at about

$175, and those with 0.0001 g resolution cost $750 and up.

Reasonably high resolution is important, because it

allows you to work to a particular level of accuracy while

using smaller amounts of materials. For example, if 0.01 g

resolution is sufficient to allow you to make up 100 mL of

a stock solution to the desired degree of accuracy, if you

instead used a 0.1 g balance, you would have to make up

1,000 mL of that stock solution to achieve the same degree

of accuracy. Similarly, if you used a 0.001 g balance, you

could make up only 10 mL of that stock solution to the

same degree of accuracy.

Capacity

Capacity specifies the maximum weight that a balance

can handle, and is related to the resolution and price of the

balance. For example, a $25 centigram balance may have a

maximum capacity of 25 g, and a $100 centigram model may

have a maximum capacity of 200 g. Note that some balances