COMPREHENSIVE

Chemistry

The study of matter and the changes it undergoes
The study of behavior, properties, and composition of matter

Analytical Chemistry

-\> Concerned with the theory and application of methods used to determine the composition of matter

Analytical Chemistry

-\> Deals with the determination of the composition of the sample and all other transformations involved in the analytical process

Analytical Chemistry

-\> A measurement of science consisting of a set of powerful ideas and methods that are useful in all fields of science and medicine

Analyst

How is a chemist often referred to as?

characteristics
components
presence, absence, quantity

Is a test or evaluation performed or conducted on a sample in order to...
-Determine its \______
-Identify its \______ or
-Determine the \_____, \_______ or the \______ of a particular substance

Sample

-A form of matter whose composition is unknown or needs to be verified
-contains the analyte and impurities

Mass (g) analyte + Mass (g) impurities

What is the formula for Mass (g) sample?

Analyte

The desired substance an analyst is looking for

-Chemical species
-Chemical constituent
-Substance of interest

Other terms for analyte:

Impurities

These are called the undesired substances

1. Inert Impurities
2. Chemically Reactive Impurities or INTERFERENCES
-impurities that affects the result of the analysis

What are the two kinds of impurities?

a) physical properties
b) quality
c) legislation
d) processes of law

An analysis is conducted on a sample in order to...
a) relate the chemical composition to \_______
b) determine the \_______ of manufactured products for routine analyses (screening, surveillance or monitoring of products) and process control
c) support \_______ such as safety, health and environmental laws or to act as reference for regulatory purposes
d) support \_______ like forensic science

Analysis or Assay

Test or Evaluation conducted on a sample

To know the composition of a substance

What is the main objective for testing or evaluating?

Qualitative Analysis

Identification of substances (elements or compounds) that are present in the sample

Quantitative Analysis

Is concerned with the determination of the relative concentration or the amount of the analyte present in the sample

I. Measurement of the mass or the volume of the sample to be analyzed.
II. Measurement of some quantity that is proportional to the amount of analyte in the sample

What are the two measurements to classify various kinds of analytical methods?

Gravimetric Method

What quantitative method determines the mass of the analyte or some compound chemically related to it?

Volumetric Method

What quantitative method determines the volume of a
solution containing sufficient reagent to react
completely with the analyte?

Electroanalytical Method

What quantitative method involve the measurement of such electrical properties as:
● VOLTAMMETRY
● AMPEROMETRY
● COULOMETRY

Spectroscopic Method
●ABSORPTION SPECTROSCOPY
● INFRARED SPECTROSCOPY
● NMR SPECTROSCOPY
● X-RAY CRYSTALLOGRAPHY

What quantitative method are based on the measurement of the interaction between electromagnetic radiation and analyte?

Minor

Major, minor, or trace?

0.01 to 1% (Limits of the analyte)

Trace

Major

\> 1%

Ultramicro

less than 0.0001 g

Complete or Ultimate

Measure the amount of all constituents present in the sample

Partial or Proximate

Measure the amount of selected constituents

Proximate Analysis

This analysis involves the determination of total protein,
fat, ash, carbohydrate, and moisture.

Formulating the Question: Defining the Problem

● Translate the general questions into specific questions
● Identify the objectives of the analysis

1. Select the Analytical Method or Procedure
2. Acquiring the Sample
3. Processing the Sample
4. Eliminating Interferences
5. Calibration and Measurement
6. Calculating the Results
7. Evaluating the Results by Estimating their Reliability

Steps in a Quantitative Analysis

-Ensure high quality analysis will be performed
-Suitability of the assay to the sample

How does one choose the analytical method appropriate for a given problem?

- accepted analytical procedures recognized by the by the Association of Official Analytical Chemists (AOAC) are used
-the level of uncertainty is within acceptable limits set by the Association of Official Analytical Chemists (AOAC)

An analysis is considered to be of high quality when

Sampling

the process of collecting a representative sample for analysis

degree of sample

Real samples generally require a \_______
preparation to remove substances that will interfere in the analysis of the desired analyte

Bulk or Gross Sample

Kind of sample that has several portions of the material to be tested

Analytical Sample

a few grams to milligrams of the laboratory sample taken to be
analyzed

Laboratory Sample

gross sample is reduced in size to a few hundred grams and is made homogeneous.

Processing the Sample

refers to the series of steps needed to convert a representative bulk sample into a homogeneous lab sample that is suitable for chemical analysis.

Preparing the Sample

What is processing the sample also referred to as?

○ Size of the analytical sample
○ How to make the sample homogeneous
○ Number of replicate measurements
○ How to put the sample in solution
○ How to deal with interferences
○ How to deal with the water present in the sample

Factors to consider prior to the processing of the sample

●Water is a common component present in samples.
● However, the moisture content of the sample changes as the sample is stored for a long period
of time
● Hence, it is not ideal to conduct an analysis on a
sample wherein the composition varies as the measurement is conducted.

Dealing with Water

Dry basis

● The moisture present in the sample is removed before weighing the analytical sample.
● The sample can be dried at ambient temperature (air drying) or by heating to a temperature \> 105°C or freeze drying.
● The analysis is carried out on the dried sample.

Wet or "As Received" Basis

● Two separate portions of the sample is obtained.
● Initially, the moisture content of the sample is
determined upon the receipt of the sample.
● A representative sample is obtained and the weight
loss is determined after drying.
● The rest of the sample is dried and all analyses
are performed on the dried sample.

solvent

most analyses are performed on solutions of sample made with a suitable \_______

rapidly and completely

he solvent should dissolve the entire sample, including the analyte, \______ and \_____

heating

if insoluble, the sample may require \_______ with strong acids, strong bases and oxidizing agents

Interference

species that causes an error in an analysis by enhancing or attenuating (decreasing) the quantity being measured.

isolated

The analyte must be \_______ from the interference before the final measurement is made.

Calibration and Measurement

●All analytical results depend on a final measurement X of a physical or chemical property of the analyte.
● The property X must vary in a known and reproducible way with the concentration of the analyte, A.

Mole

the amount of a substance that contains as many elementary entities as there are atoms in exactly 12 grams of 12C

chemical reaction

A process in which one or more substances is changed into one or more new substances is a

chemical equation

A \_______ uses chemical symbols to show what happens during a chemical reaction

Limiting reagent

reactant used up first in the reaction

Excess reagent

reactants present in quantities greater than necessary to react with the quantity of the limiting reagent

Solution

a chemical mixture that has a uniform distribution for all its components

Solvent

the most abundant solution (or the component that is used to dissolve and contain the other chemicals)

Solute

all other substances in the mixture

Chemical Concentration

Refers to the unit of concentration that indicates to how much solute is contained in a given volume or mass of the solution or solvent

Density

ratio of mass to volume occupied by the substance/material

Specific Gravity

ratio of the mass of a substance to the mass of an equal volume of water

Dilution
lower concentration: diluted solution
more concentrated: stock solution

process used to prepare a solution of lower concentration from a more concentrated solution

measure of central tendency

refers to a single value that will represent the body of data that was collected.

Absolute error

difference between the experimental result (χi) and true value (μ).

systematic error

causes the mean of a set of data to differ from the accepted value.

acids

substances that ionize in water to produce H+ ions -Arrhenius

bases

substances that ionize in water to produce OH- ions -Arrhenius

acids

-sour taste
-aqueous \_____ conduct electricity
-react w certain metals to produce hydrogen gas
-react etcetc

bases

-bitter taste
-change litmus from red to blue
-slippery
-aqueous \_____ solutions conduct electricity

strong, completely

strong acids and base \= \____ electrolytes
strong electrolytes are \_____ ionized in solution

Monoprotic acids

each unit of the acid yields one hydrogen ion upon ionization

Diprotic acid

each unit of the acid gives up two H ions in two separate steps:

Triprotic acids

yield three H ions and relatively few in number

neutralization

A \________ reaction is a reaction between acid and a base

Titrimetric analysis, titration

\_____ refers to the use of the analytical technique referred to as the \______

Titration Methods

\__________ include a group of quantitative procedures based on determining the quantity of a reagent of known concentration that is required to react completely with the analyte

Volumetric Titrimetry

measures the volume of a solution of known concentration that is needed to react completely with the analyte

requires the use of a buret with high precision

Limitation of volumetric titrimetry:

Gravimetric or weight titrimetry

measures the mass of the solution of known concentration that is needed to react completely with the analyte

requires the use of sensitive analytical balance

Limitation of Gravimetric or weight titrimetry

Coulometric Titrimetry

type of titrimetry in which the quantity of charge in coulombs required to complete a reaction with the analyte is measured

titrant

The solution added in small and precise increment is called a

equivalence point, theoretical

The \_______ of a titration cannot be determined experimentally because it is a \_____ stage

endpoint

The \_____ is the stage when the reaction is observed to be complete

titration

a process in which a standard reagent is added to a solution of an analyte until the reaction between the analyte and reagent is judged to be completed

Indicators

Added to the analyte solution to give an observable physical change at or near the equivalence point

standard solution

A \____ \___ is a reagent of known concentration that is used in a titrimetric analysis

direct method and standardization

two basic methods to establish concentration:

direct method

carefully weighed quantity of a primary standard is dissolved in a suitable solvent and diluted to a known volume in a volumetric flask

Standardization

the titrant to be standardized is used to titrate (1) a weighed quantity of a primary standard, (2) a weighed quantity of a secondary standard, (3) a measured volume of another standard solution

highly purified reference

a primary standard is \_______ material used in titrimetric methods

secondary standard

Compound whose purity has been established by chemical analysis that serves as the reference material for a titrimetric method of analysis

stoichiometric

The reaction must have a well-defined balanced chemical equation, meaning that the reaction must be \______

rapid

the rate of the reaction is very fast or instantaenous, meaning that the reaction must be \_____

quantitative

-the reaction must favor the formation of the products
-the equilibrium constant of the reaction is very large

neutralization titrations

reaction between acid and base resulting to water and salt as products

strong acids and strong bases

the substances that produce the most remarkable or pronounced change in the pH of the titration mixture at the equivalence point are \______

against

to standardize solutions, determine the concentration of the titrant by reacting the titrant \___ a primary standard

NaOH

most common titrant solution

KOH (potassium hydroxide), Ba(OH)2 (barium hydroxide)

other possible titrant solutions