CHAPTER 0: THE ANALYTICAL PROCESS

Question 1

Homogenous:

Answer 1

Same Throughout

Question 2

Heterogeneous:

Answer 2

Differs from region to region

Question 3

Sampling:

Answer 3

Procuring a representative sample to measure, which is the first step in any chemical analysis.

Question 4

Decant:

Answer 4

To pour liquid off a solid or, perhaps, a denser liquid. The denser phase is left behind.

Question 5

Aliquot:

Answer 5

A Portion

-normally a precise liquid sample taken for analysis.

Question 6

Analyte:

Answer 6

Substance being measured or detected.

Question 7

Aqueous:

Answer 7

In water (to be considered Aqueous).

Question 8

Calibration Curve:

Answer 8

A graph showing the value of some property versus concentration of analyte. When the corresponding property of an unknown is measured, its concentration can be determined from the graph.

Question 9

Composite Sample:

Answer 9

A representative sample prepared from a heterogeneous material. If the material consists of distinct regions, the composite is made of portions of each region, with relative amounts proportional to the size of each region.

Question 10

Interference and when it occurs:

Answer 10

A phenomenon in which the presence of one substance changes the response in the analysis of another substance
—– Interference occurs when a species other than the analyte causes an analysis to be inaccurate.

Question 11

Masking:

Answer 11

Process of adding a chemical substance (a masking agent) to a sample to prevent one or more components from interfering in a chemical analysis..

-refers to the transformation of an interfering species into a form that is not detected.

Question 12

Qualitative Analysis:

Answer 12

Process of determining the identity of the constituents of a substance.

Question 13

Quantitative Analysis

Answer 13

Process of measuring how much of a constituent is present in a substance.

Question 14

Quantitative Transfer:

Answer 14

Transfer of the entire contents from one vessel to another. This process is usually accomplished by rinsing the first vessel several times with fresh liquid and pouring each rinse into the receiving vessel.
—–is a complete transfer of material regardless of state.

Question 15

Random heterogeneous Material:

Answer 15

• A material in which there are differences in composition with no pattern or predictability and on a fine scale.
• When you collect a portion of the material for analysis, you obtain some of each of the different compositions.

Question 16

Random Sample:

Answer 16

Bulk sample constructed by taking portions of the entire lot at random.

Question 17

Sample Preparation:

Answer 17

Transforming a sample into a state that is suitable for analysis. This process can include concentrating a dilute analyte and removing or masking interfering species.

Question 18

Sampling:

Answer 18

The process of collecting a representative sample for analysis.

Question 19

Segregated Heterogeneous Material:

Answer 19

A material in which differences in composition are on a large scale. Different regions have obviously different composition.

Question 20

Slurry:

Answer 20

A suspension of a solid in a solvent

Question 21

Species:

Answer 21

Chemists refer to any element, compound, or ion of interest as a Species. (single & plural)

Question 22

Standard Solution:

Answer 22

A technique in which an analytical signal due to an unknown is first measured. Then a known quantity of analyte is added, and the increase in signal is recorded. From the response, it is possible to calculate what quantity of analyte was in the unknown

Question 23

Supernatant (Supernate) Liquid:

Answer 23

Liquid remaining above the solid after precipitation.

Question 24

The sampling technique is very important when analyzing a large area or vast amounts of material because you cannot analyze everything. When preparing a composite sample, a chemist would:

Answer 24

take representative samples from various areas of the bulk samples and combine them for analysis.

Question 25

The steps in a chemical analysis are

Answer 25

1. Formulate the question.
   2. Select the analytical procedure.
   3. Sample.
   4. Prepare the sample.
   5. Make replicate measurements of the sample.
   6. Make a clear and complete written report of your findings.

Question 26

When performing an analysis a chemist often uses a standard solution. What is a standard solution?

Answer 26

A solution that has a concentration of a chemical that is known to a high degree of certainty.

Question 27

The uncertainty in the measurement is as important as the

Answer 27

measurement itself because it tells you how reliable the measurement is.

Question 28

A detector response may be different for analytes with equal concentrations; therefore,

Answer 28

a calibration curve must be constructed.

Question 29

Analysis of unknown is meaningless unless you have

Answer 29

collected the sample properly, taken measures to ensure the reliability of the analytical method, and communicated your results clearly and completely.