Chapter 8 - Introduction to Analytical Chemistry Flashcards
It is the science of obtaining, processing, and communicating information about the composition and structure of matter
Analytical Chemistry
Analyrtical Chemistry is the ____ and ____ of determining what _____ __ and how much of it _____
- art and science
- matter is
- exists
Analytical chemistry is a ______ ____ consisting of a set of ____ ____ and _____ that are useful in all fields of _____ and ______
- measurement science
- powerful ideas and methods
- science and engineering
Both _____ and _____ information are required in an analysis
Qualitative and Quantitative
The role of analytic chemistry
is applied throughout industry, medicine, and all the science
The role of quatitative analytical measurements
play a vital role in chemistry, biochemistry, biology, geology, physics, and the other sciences
The _______ _____ of chemical analysis makes it a vital tool in medical, industrial, government, and academic laboratories throughout the world
interdisciplinary nature
It reveals the identity of the elements and compounds in a sample
Qualitative analysis
Qualitative analysis reveals the ______ of the elements and compounds in a sample
identity
It indicates the amount of each substance in a sample
Quantitative analysis
Quantitative analysis indicates the _____ of each substance in a sample
amount
It is based on obsevations (involves the senses)
Qualitative Data
It is based on numbers (measurement or counting)
Quantitative Data
Qualitative Data is based on
observation (involves the senses)
Quantitative Data is based on
numbers (measurement or counting)
It is a chemical substance that is the subject of a chemical analysis
Analyte
The results of a typical quantitative analysis are computed from two measurements:
- Mass or volume (gravimetric and volumetric methods)
- Measurement of some quantity that is proportional to the amount of analyte in the sample (electrochemical and spectrometric methods)
Quantitative analytical methods (classification)
- Gravimetric methods
- Volumetric methods
- Electroanalytical methods
- Spectroscopic methods
Gravimetric methods determine the _____ of the analyte or some compound chemically related to it
mass
Gravimetric methods is basen on what principle?
Based on the principle of precipitation or volatilization methods
Volumetric methods determine the ______ of a solution containing sufficient reagent to react completely with the analyte
volume
What measurement is involve in Volumetric methods?
Measurement of the volume of a solution of known concentration, referred to as the titrant
Electroanalytical methods involve the measurement of such ____ _____
electrical properties
Measurement of electrical properties
- voltage
- current
- resistance
- quantity of electrical charge
Spectroscopic methods are based on measurement of the interaction between ______ ______ and _____ ____ or molecules or on the ______ of such ______ by analytes.
- electromagnetic radiation
- analyte atoms
- production of such radiation
General steps in a quantitative analysis
- Selec method
- Acquire sample
- Process sample:
(1) Is sample soluble? (If no, carry out chemical dissolution) and (If yes, proceed to step 5)
(2) Measurable property? (If no, change chemical form) and (If yes, proceed to step 6) - Eliminate interferences
- Measure proerty X (Calibration and Measurement)
- Calculate results
- Estimate reliability of results
In picking a method, what is the first question to be considered?
The level of accuracy required
Second consideration in picking a method
Related to economic factors is the number of samples to be analyzed
It always influence the choice of method to some degree
Complexity of the sample and the number of components in the sample
In acquiring a sample, ______ involves obtaining a ____ ____ of a material whose composition accurately ______ the ____ of the material being samples
- Sampling
- small mass
- represents the bulk
Sampling is frequently the most ______ step in an analysis and the _____ of ____ ____
- difficult
- source of greatest error
A material is ______ if its constituent parts can be distinguished visually or with the aid of a microscope
heterogeneous
How can you say if the material is heterogeneous in acquiring the sample?
If its constituent parts can be distinguished visually or with the aid of a miscroscope
It is the process of determining how much of a given sample is the material indicated by its name
Assay
Under _____ circumstances, no sample processing is required prior to the measurement step
certain
Under _____ circumstances, we must process the sample in any of a variety of different ways
most
First step in processing the sample
The preparation of a laboratory sample
In preparing a laboratory sample, a solid sample is ____ to decrease particel size, _____ to ensure homogeneity, and stored for various lengths of time before analysis begins
- ground
- mixed
It is good ideas to ____ _____ just before starting analysis because any ____ or ____ of water changes the chemical composition of _____
- dry sample
- loss or gain
- solids
What samples are subject to solvent evaporation?
Liquid
Alternatively, the _____ ____ of the sample can be determined at the time of the analysis in a _____ _____ _____
- moisture content
- separate analytical procedure
If the analyte is a ____ dissolved in a liquid, analyte must be kept inside a _____ _____ _____ to prevent ______ by ________ _____
- gas
- inside a second seales container
- contamination
- atmospheric gases
What is required to preserve the integrity of the sample?
Extraordinary measures
- sample manipulation
- measurement in an inert atmosphere
It is a 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 or replicates
Replication improves the ______ of the _____ and provides a ______ of their ______
- quality of the results
- provides a measure of their reliability
________ measurements on replicates are usually _____, and various _____ ____ are performed on the results to _____ their _____
- Quantitative
- averaged
- statistical tests
- establish their reliability
In preparing solutions: physical and chemical changes, _____ should dissolve the entire sample, including the _____, _____ and _____
- solvent
- analyte
- rapidly and completely
Samples that requires heating
Aqueous solutions of strong acids, strong bases, oxidizing agents, reducing agents, or some combination of such reagents
It may be necessary to _____ the sample in ___ or _____ or perform a _________ _____ of the sample in the presence of various _____
- ignite
- air or oxygen
- high-temperature fusion
- fluxes
It is a species other than analyte that affect the final measurement
Interferences, or interferents
An interference is a species that _____ an ____ in an analysis by ______ or _______ (making smaller) the quantity being measured
- causes an error
- enhancing or attenuating
Techniques or reactions that work for only one analyte are said to be ______
specific
Tehniques or reactions that apply for only a few analytes are _____
selective
It is called to all of the components in the sample containing an analyte
Matrix or Sample Matrix
The measurement of the ______ is _____ _____ to the _____ (C sub A)
- property X
- directly proportional
- concenration
Formula for calibration and measurement
CA = kX
where k is a proportionality constant
Basis of calculating the results
based on the raw experimental data collected in the measurement step, the characteristics of the measurement instruments, and the stoichiometry of the analytical reaction
Analytical results are ______ without an ______ of their ______
- incomplete
- estimate of their reliability
It is used to determine if the standard deviation (σ) of a set of data is small or large when compared to the mean (µ)
Relative Standard Deviation (RSD) or Coefficient of Variation (CV)
The relative standard deviation can tell you how ______ the average of your results is
precise
A ________ provides a number called ________ that is directly proportional to the _____ ______ , which is also proportional to the ______ of the ______ responsible for the _____
- spectrophotometer
- absorbance
- color intensity
- concentration of the species
- color
