Chapter 2: Chemicals, Apparatus, and Unit Operations of Analytical Chemistry Flashcards
Classifying chemicals
chemicals conform to the minimum standards set forth by the Reagent
Chemical Committee of the American Chemical Society (ACS)1 and are used whenever possible in analytical work.
reagent-grade chemicals
these kinds of reagent have been carefully analyzed by the supplier, and the results are printed on the container label.
primary standard chemicals
Meaning of NIST
National Institute of Standards and Technology
is an excellent source for primary standards. This agency also prepares and sells reference standards
NIST
are complex substances that have been exhaustively analyzed.
reference standards
3 different classifications of chemicals
Reagent grade
primary standard grade
special-purpose reagent chemicals
Chemicals that have been prepared for a specific application are also available.
Included among these are solvents for spectrophotometry and high-performance
liquid chromatography.
Special-Purpose Reagent Chemicals
TRUE or FALSE
Select the best grade of chemical available for analytical work. Whenever possible, pick the smallest bottle that is sufficient to do the job.
FALSE
TRUE or FALSE
Do not hold the stoppers of reagent bottles between your fingers. Never set a stopper on a desk top.
FALSE
TRUE or FALSE
Unless directed otherwise, never insert spatulas, spoons, or knives into a bottle that contains a solid chemical. Instead, shake the capped bottle vigorously or tap it gently against a wooden table to break up an encrustation. Then pour out the desired quantity. These measures are occasionally ineffective, and in such cases a clean porcelain spoon should be used.
TRUE
The apparatus should be washed with a ____________ and rinsed with _____________ and finally with ______________.
hot detergent; tap water; deionized water
TRUE or FALSE
It is seldom necessary to dry the interior
surface of glassware before use. Drying is usually a waste of time and is always a potential source of contamination
TRUE
TRUE or FALSE
An organic solvent, such as methyl ethyl ketone or acetone, may be effective in
removing grease films.
TRUE
is the sudden, often violent
boiling that tends to spatter solution
out of its container.
bumping
is the oxidation of the
organic constituents of a sample with
oxidizing reagents such as nitric acid,
sulfuric acid, hydrogen peroxide, aqueous
bromine, or a combination of
these reagents.
wet ashing
may also minimize bumping if their use is permissible
glass beads
TRUE or FALSE
Organic constituents can frequently be eliminated from a solution by adding sulfuric acid and heating to the appearance of sulfur trioxide fumes (in a hood).
TRUE
must be used to measure masses with high accuracy.
analytical balance
is an instrument for determining mass with a maximum capacity
that ranges from 1 g to a few kilograms with a precision of at least 1 part in
105 at maximum capacity.
analytical balance
TRUE or FALSE
The precision and accuracy of many modern analytical balances exceed 1 part in 10^6 at full capacity.
TRUE
Types of analytical balance
macrobalances
semimicroanalytical balances
microanalytical balance
have a maximum capacity
ranging between 160 and 200 g. With these balances, measurements can be made with a standard deviation of 60.1 mg.
macrobalances
have a maximum
loading of 10 to 30 g with a precision of 60.01 mg
Semimicroanalytical balances
has a capacity of 1 to 3 g and a precision of 60.001 mg (1 μg).
microanalytical balance