Complexometric Titration

OXIDATION

algebraic increase in oxidationm number of an atom

REDUCTION

algebraic decrease in oxidation nuber

Reducing Agent

atom that undergoes oxidation

Oxidizing Agent

atom/ion that undergoes reduction

Redox Ttiration

type of titration in which titrant has oxidation-reduction properties

Oxidimetry

titration wherein the titrant is an oxidizer

Reducimetry

titrant is a reducer

Factors affecting inflection point values in titration curve

Nature of analyte and titrant and value of pH medium

Winkler method

determines the amount of dissolved oxygen in a water stream

Winkler Method General Procedure

1. Sampling Preparation of reagants, sodium thiosulfate solution

2. Determine the concentration of sodium thiosulfare solution by titrating against a primary standard potassim dichromate

3. Preparation Via Winkler Method

4. Titrate sample with standardized thiosulfate solution

5. Calculation of ppm DO

Spectrospcopy

tool to study the elucidation of the structure of molecular species as well as the quantitative determination of both inorganic and organic compound

Spectroscopy studies

interaction of electromagnetic radiation and matter

amount of radiation absorbed is measured

at varying wavelengths

Gamma ray

Spectroscopic technique:Mossbauer spectroscopy

Types of transition: Nuclear

X-ray

Spectroscopic technique: x-ray absorption & flourescence

Type of transition: Removal of core electron, bond/breaking/ionization

UV/Vis

Spectroscopic technique: UV/Vis spectroscopy, atomic emission, flourescence spectroscopy, phosporescence, and atomic flourescence

Types of transition: Electronic excitation of valence electron

IR

Spectrsocopic technique: Infrared spectroscopy

Types of transition: Vibration of molecular bonds

microwave

Spectroscopic technique: microwave spectroscopy

Types of transition: Molecular rotation, electron spin

Radiowave

Spectroscopic technique: electron spin resonance & nuclear magnetic resonance

Types of transition: nuclear spin

Absorption spectroscopy

photon is absorbed by an atom or molecule, which undergoes transition to form a lower-energy state to a higher energy or excited stage

emission

sample is excited by applying heat or electricity. When the electrons return to ground state, they emit radiation characteristics of a given atom

Line source

emits radiation at selected wavelengths

Continuum source

emits radiation over a broad range of wavelengths with a relatively smooth variation in intensity

Wavelength selector

isolates the desired wavelength band so that the only band of interest is detected and measured

enhances both selectivity and sensitivity of the instrument

monochromator

most commpon example of wavelength selector

Radiation Detector

converts radiate energy to measurable electric signals

Photomultiplier

most commonly used detector in UV-Vis spectrometer which works via photoelectric effect

Signal processor

displays a transducer’s electric signal in a form that is more convenient for the analyst

Quantitative analysis for a single sample

amount of light aborbed by analyte is expressed in 2 ways: transmittence and absorbance

Transmittance

ratio of transmitted radiant power (P) to the incident radiant power (P0)

Absorbance

amount of light absorbed by the sample = logarithm of the inverse of transmittance

Factors affecting absorbance

1. Concentration

2. Pathway of the sample

3. Structure of the molecules

Beers Law

within limits there is a linear relationship between absorbance and concentration

Factors Affecting Oxygen Levles

1. Oxygen is removed from the water by chemical reactions, decay and respiration

2. Water temperature and atmospheric pressure

3. Cold water =high atm - more dissolved oxygen

4. Turbidity and degree of water turbelence