Chapter 1: The Nature of Analytical Chemistry Flashcards
measure electrical properties such as potential, current, resistance, and quantity of
electrical charge.
electroanalytical methods
determine the mass of the analyte or some compound chemically related to it
gravimetric method
we measure the volume of a solution containing sufficient reagent to react completely with the analyte
volumetric method
explore the interaction between electromagnetic radiation and analyte atoms or molecules or the emission of radiation by analytes
spectroscopic methods
name other methods
mass-to-charge ratio of ions by mass spectrometry,
rate of radioactive decay,
heat of reaction,
rate of reaction,
sample thermal conductivity,
optical activity, and
refractive index
essential first step in any quantitative analysis is the
selection of a method
Steps of quantitative analysis
Select a method
acquire sample
process sample
is sample soluble –> carry out chemical dissolution (NO)
measurable property –> change chemical form? (NO)
eliminate interferences
measure property X
calculate results
eliminate reliability of results
a material is _________ if its
constituent parts can be distinguished
visually or with the aid of a microscope.
heterogeneous
the process of collecting a small mass of a material whose composition accurately represents the bulk of the material being sampled
sampling
is frequently the most difficult step in an analysis and the source of the greatest error
sampling
improves the quality of the results and
provides a measure of their reliability
replication
Most chemical analyses are performed on __________ whose masses or volumes have been determined by careful measurements with an analytical balance or with a precise volumetric device.
replicate samples
Species other than the analyte that affect the final measurement are called
interferences or interferent
What kind of analysis reveals the identity of the elements and compounds in a sample.
Qualitative analysis
What kind of analysis indicates the amount of each substance in a sample.
Quantitative analysis
components of a sample that are determined
analyte
It is the process of determining how much of a given sample is the material by its indicated name. For example, a zinc alloy is assayed for its zinc content, and its assay is a particular numerical value.
assay
are portions of a material of approximately the same size that are carried through an analytical procedure at the same time and in the same way.
replicate samples / replicates
is a material, often an alkali metal salt, that is mixed with the sample and heated to form a fused salt.
flux
a species that causes an error in an analysis by enhancing or attenuating (making smaller) the quantity being measured.
interference / interferent
is the collection of all the components in the sample containing an analyte.
matrix / sample matrix
Techniques or reactions that work
for only one analyte are said to be
specific
Techniques or reactions
that apply to only a few analytes are
selective
is the process of determining the proportionality between analyte concentration and a measured quantity.
calibration
The process of determining k is thus an important step in most analyses; this step is called a
caliibration
TRUE or FALSE
An analytical result without an
estimate of reliability is of no
value.
TRUE
The process of continuous measurement and control is often referred to as a
feedback system
the cycle of measurement, comparison, and control is called
feedback loop
