Analytical Chemistry Chapter 1

Question 1

Measurement science consisting of a set of powerful ideas and methods that
are useful in all fields of science, engineering, and medicine

Answer 1

Analytical Chemistry

Question 2

Establishes the chemical identity of the
species in the sample

Answer 2

Qualitative Analysis

Question 3

Determines the relative amounts of these species, or analytes, in numerical terms.

Answer 3

Quantitative Analysis

Question 4

An integral part of the separation step.

Answer 4

Qualitative Analysis

Question 5

Essential adjunct to quantitative analysis.

Answer 5

Determining the identity of the
analytes

Question 6

Are the components of a
sample that are determined.

The substance being determined.

Answer 6

Analytes

Question 7

What is the role of Analytical Chemistry?

Answer 7

It is applied throughout industry, medicine, and all the sciences.

Question 8

Give Example of Role of Analytical Chemistry

Answer 8

Conc. of Oxygen and carbon dioxide - treat illnesses.

Hydrocarbons, nitrogen oxides, and carbon monoxide - emission-control devices in automobile.

Ionized calcium - parathyroid disease.

Quantitative determination of nitrogen in foods - protein content and nutritional value.

Analysis of steel - adjustment in
the concentrations of such elements as carbon, nickel, and chromium to achieve
a desired strength, hardness, corrosion resistance, and ductility.

The mercaptan content of household gas - odor to warn of dangerous leaks.

Farmers tailor fertilization and irrigation - plant needs,, gauging these needs from quantitative analyses of plants and soil.

Question 9

Play a vital role in many research areas in chemistry, biochemistry, biology, geology, physics, and the other sciences.

Answer 9

Quantitative analytical measurements

Question 10

Archaeologists identify the sources of volcanic
glasses (obsidian) by___________ in samples taken from various locations.

Answer 10

Measuring concentrations of minor elements

Question 11

Draw the figure 1-1. The relationship between analytical chemistry, other branches of chemistry, and the other sciences.

Question 12

Often called the central science; its top-center position and the central position of analytical chemistry in the figure emphasize this importance.

Answer 12

Chemistry

Question 13

What makes a chemical analysis a vital tool in medical, industrial, government, and
academic laboratories throughout the world.

Answer 13

The interdisciplinary nature of chemical analysis.

Question 14

Enumerate the Quantitative Analytical Methods

Answer 14

Gravimetric methods
Volumetric method
Electroanalytical methods Spectroscopic methods

Question 15

Determine the mass of the
analyte or some compound chemically related to it

Answer 15

Gravimetric Methods

Question 16

Measures the volume of a solution containing sufficient reagent to react completely with the analyte.

Answer 16

Volumetric Method

Question 17

Measure electrical properties such as potential,
current, resistance, and quantity of electrical charge

Answer 17

Electroanalytical Methods

Question 18

Explore the interaction between electromagnetic radiation and analyte atoms or molecules or
the emission of radiation by analytes

Answer 18

Spectroscopic Methods

Question 19

In a group of miscellaneous methods, what do we measure?

Answer 19

we measure such quantities as:

mass spectrometry
rate of radioactive decay
heat of reaction
rate of reaction
sample thermal conductivity
optical activity
refractive index

Question 20

Draw figure 1-2, steps in quantitative analysis

Question 21

The essential first step in any quantitative analysis is the____

Answer 21

selection of a method

Question 22

One of the first questions that must be considered in the selection process
is the_________.

Answer 22

level of accuracy required

Question 23

A second consideration related to economic factors is the____

Answer 23

number of samples that
will be analyzed

Question 24

What influence the choice of method to some degree in quantitative analysis?

Answer 24

Finally, the complexity of the sample and the number of components in the sample

Question 24

the second step in a quantitative analysis is to

Answer 24

acquire the sample

Question 25

A material is __________if its constituent parts can be distinguished visually or with the aid of a microscope. Coal, animal tissue, and soil are heterogeneous.

Answer 25

heterogeneous

Question 26

An ________ is the process of determining how much of a given sample is the material by its indicated name. e. For example, a zinc alloy is assayed for its zinc content, and its _______ is a particular numerical value.

Answer 26

assay

Question 27

Is the process of collecting a small mass of a material whose composition accurately represents the bulk of the material being sampled.

Answer 27

Sampling

Question 28

the third step in an analysis is to_______

Answer 28

process the sample

Question 29

Under most circumstances, the sample is processed in one of the several different ways. The first step in processing the sample is often the __________

Answer 29

preparation of a laboratory sample

Question 30

In preparing a laboratory sample: A solid laboratory sample is _____ to decrease particle size, _______ to ensure homogeneity, and ______ for various lengths of time before analysis begins. _________ of water may occur during each step, depending on the humidity of the environment. Because any loss or gain of water changes the chemical composition of solids, it is a good idea to _______ samples just before starting an analysis. Alternatively, the moisture content of the sample can be determined at the time of the analysis by a ________. Liquid samples present a slightly different but related set of problems during the preparation step. If such samples are allowed to stand in open containers, the solvent may __________. If the analyte is a gas dissolved in a liquid, as in our blood gas example, the sample container must be kept inside a ________, perhaps during the entire analytical procedure, to prevent contamination by atmospheric gases. may be required to preserve the integrity of the sample.

Answer 30

ground, mix, stored absorption/desorption dry separate analytical procedure evaporate and change the concentration of the analyte second sealed container sample manipulation and measurement in an inert atmosphere

Question 31

Preparing Solutions: Physical and Chemical Changes Because many classical methods and most instrumental techniques use solution samples, most analyses are performed on solutions of the sample made with a suitable ________ Unfortunately, many materials that must be analyzed are insoluble in common solvents. Examples include:______ ________Is often the most difficult and time-consuming task in the analytical process. The sample may require heating with_____________ It may be necessary to ignite the sample in _________ of the sample in the presence of various fluxes. Is a material, often an alkali metal salt, that is mixed with the sample and heated to form a fused salt.

Answer 31

solvent silicate minerals, high-molecular-mass polymers, and specimens of animal tissue. Converting the analyte into a soluble form aqueous solutions of strong acids, strong bases, oxidizing agents, reducing agents, or some combination of such reagents. air or oxygen or to perform a high-temperature fusion Flux

Question 32

In defining replicate samples Most chemical analyses are performed on replicate samples whose masses or volumes have been determined by careful measurements with an ________. Improves the quality of the results and provides a measure of their reliability. 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

Answer 32

analytical balance or with a precise volumetric device Replication Replicate samples, or replicates

Question 32

Calibrating and Measuring Concentration: Formula: Stands for: cA k X The process of determining k is thus an important step in most analyses; this step is _________ Process of determining the proportionality between analyte concentration and a measured quantity. Is the collection of all the components in the sample containing an analyte. Techniques or reactions that work for only one analyte are said to be _______. Techniques or reactions that apply to only a few analytes are _______.

Answer 32

cA = kX cA- Concentration of the analyte k- proportionality constant X - final measurement of a physical or chemical property of the analyte Calibration matrix, or sample matrix specific selective

Question 33

In Eliminating Interferences: Once we have the sample in solution and converted the analyte to an appropriate form for measurement, the next step is to ___________ Few chemical or physical properties of importance in chemical analysis are unique to a single chemical species. Instead, the reactions used and the properties measured are ___________. Species other than the analyte that affect the final measurement are called ______ species that causes an error in an analysis by enhancing or attenuating (making smaller) the quantity being measured.

Answer 33

eliminate substances from the sample that may interfere with measurement characteristic of a group of elements of compounds interferences, or interferents

Question 34

Calculating Results Computing ______ from experimental data is usually relatively easy, particularly with computers. This step is depicted in the next-to-last block of the flow diagram of Figure 1-2. These computations are based on the________________

Answer 34

analyte concentrations calculate results 1. Raw experimental data collected in the measurement step 2. Characteristics of the measurement instruments 3. Stoichiometry of the analytical reaction.

Question 34

Evaluating Results by Estimating Reliability analytical results are complete only when their _______.

Answer 34

reliability has been estimated

Question 34

Process of continuous measurement and control is often referred to as a _______, Cycle of measurement, comparison, and control is called a__________. Draw figure 1-3

Answer 34

feedback system feedback loop

Question 34

Scientists throughout the world have adopted a standardized system of units known as the_____________

Answer 34

International System of Units (SI)

Question 35

is an unchanging measure of the quantity of matter. is the force of gravitational attraction between that matter and Earth

Answer 35

Mass m Weight w

Question 35

The SI unit for the amount of a chemical substance. It is always associated with specific microscopic entities such as atoms, molecules, ions, electrons, other particles, or specified groups of such particles as represented by a chemical formula

Answer 35

mole

Question 36

The fixed number 6.02214076 x 1023 is known as

Answer 36

Avogadro’s constant

Question 37

The ______ of a substance is the mass in grams of 1 mole of that substance.

Answer 37

The molar mass M

Question 38

Is the closeness of results to others obtained in exactly the same way.

Answer 38

Precision

Question 39

Is the closeness of a measured value to the true or accepted value.

Answer 39

Accuracy

Question 39

The_________ of a measurement is the difference between the measured value and the true value. The sign of the absolute error tells you whether the value in question is high or low. If the measurement result is low, the sign is ______; if the measurement result is high, the sign is _________.

Answer 39

absolute error negative positive

Question 40

The _______ of a measurement is the absolute error divided by the true value.

Answer 40

relative error

Question 41

Types of Errors in Experimental Data Causes data to be scattered more or less symmetrically around a mean value. affect measurement precision. They arise from experimental variables that cannot be controlled or determined. Examples include: random fluctuations in electrical noise, random inconsistencies in measurement readings, or random changes in laboratory temperature

Answer 41

random (or indeterminate) error

Question 42

causes the mean of a data set to differ from the accepted value. These errors often occur when instruments or measuring devices are uncalibrated or are calibrated improperly. They have the same effect on all samples. Systematic errors can be very subtle and difficult to detect, but finding and eliminating them is an integral part of the measurement process.

Answer 42

systematic (or determinate) error

Question 43

Occur infrequently and often result from an experimental blunder such as misreading a scale or interpreting a number incorrectly They usually occur only occasionally, are often large, and may cause a result to be either high or low. They are often the product of human errors.

Answer 43

Gross errors