An analytical balance is an extremely accurate piece of equipment used
for determining weights of various items. An analytical balance
used for the total suspended solids test must be capable of weighing to
Beakers are used for mixing chemicals and as containers for samples
during testing. The lip at the top makes beakers easy to use for
the flat bottom and straight sides makes boiling or heating easy.
used for mixing, the straight sides make the use of some type of
stirring equipment necessary. Note: As with
Erlenmeyer flasks, the graduation marks on beakers are only approximate
volumes. Beakers should not be used when accurate volume
measurements are required.
Basically, burettes are long, graduated glass tubes that have a valve
(called a stop-cock) for use in dispensing accurate volumes of
chemicals. Burettes are used for titration, which is the method
for accurately measuring out exact amounts of one chemical into another
to produce a desired chemical reaction. The Winkler method for
the determination of dissolved oxygen and the Iodometric method for
chlorine residual are two tests using burettes for titrations
Made of rubber with a glass drain tube, crucible holders provide a seal
between the crucible and filter flask. When a seal is formed,
suction can be applied to the filter flask creating a vacuum inside the
flask, which pulls water in the sample out of the crucible.
Desiccators are containers which are used to provide a moisture-free
environment for cooling and storing objects and chemicals. The
top and bottom fit
together to form an airtight seal. The bottom section of the
desiccator contains a chemical (desiccant) which absorbs moisture from
the air. Hinged desiccator cabinets are also available for this
Dissolved oxygen meters measure the concentration of dissolved oxygen
A drying oven is used for drying samples, glassware and crucibles to
constant weight. Gravity convection ovens circulate air in the
oven through holes at the top and bottom of the oven. This
circulation of air keeps the temperature even throughout the oven and
keeps the humidity low.
The primary use for Erlenmeyer flasks is in mixing chemicals.
Because the sides of Erlenmeyer flasks are slanted and the mouth is
narrow, mixing reagent liquids can be accomplished by swirling without
fear of spilling the contents. The advantage of this type of
flask is that special stirring equipment (such as a magnetic stirrer)
is not needed. Note: Although many Erlenmeyer
flasks have volume markings, they are approximate volumes
only. The graduations on Erlenmeyer flasks should not be
used when accurate measurements are required.
Filter flasks are Erlenmeyer flasks with an adapter (called a side-arm)
near the top. A rubber hose is attached to the side-arm and
connected to a vacuum pump or aspirator. When suction is applied,
air is drawn out through the side-arm and a vacuum is created inside
Gooch crucibles are used in the suspended solids test. The
bottom of the crucible is covered with holes. When a glass fiber
filter is placed in the bottom of the crucible and sample is added, the
water can be drawn though the filter by applying a vacuum to the bottom
of the crucible. Gooch crucibles are made of porcelain to
withstand repeated reheating and high temperatures.
Graduated cylinders are glass or plastic tubes that are calibrated for
measuring liquid volumes. Although not nearly as accurate as
pipettes, graduated cylinders have an advantage in that they require
much less technique to use. This allows for more reproducible
results for those who are unfamiliar with proper laboratory techniques.
A muffle furnace is a kiln type oven, capable of maintaining extremely
high temperatures for extended periods of time. Muffle furnaces
are used primarily for igniting organic solids in the determination of
A pH meter is an instrument which measures the intensity of the
alkalinity or acidity of a solution by electrically measuring the
change in current between a reference electrode and a glass pH
Basically, pipets are specially designed and calibrated glass
tubes used for accurately transferring small volumes of solution
(usually 50 mL or less) from one container to another. Pipets are
available in a
variety of types and sizes, for many different uses.
A spectrophotometer is an instrument capable of producing light at a
specific wave length, and then measuring the amount of that light which
passes through a colored liquid. Spectrophotometers are used
whenever the intensity of the color in a solution needs to be measured
to determine the concentration of a chemical.
Order time and order freshness should be taken into account when
ordering laboratory materials.
Primarily used in the suspended solids test, tongs are special devices
for grasping glassware. It is very important to use tongs for
handling crucibles to keep skin oil off the sides and to prevent burns.
A turbidometer is used to measure turbidity.
A Vernier Protractor is used to make an engineer's drawing.
Volumetric flasks are specially designed containers for very accurate
mixing and diluting. Like volumetric pipettes, volumetric flasks
designed to measure one volume only. The long neck makes it easy
determine when the final volume has been reached.