ANACHEM L7-L9

Electric Charge

Measured in coulombs (C); quantity of electricity.

Faraday Constant

Equal to 9.649 × 10^4 coulombs; represents charge per mole of electrons.

Electric Current

Flow of electric charge per second through a circuit; measured in amperes (A).

Electric Potential

Energy per unit charge that drives electron movement; measured in volts (V).

Redox Reaction

Reaction involving transfer of electrons.

Oxidizing Agent

Substance that gains electrons and is reduced.

Reducing Agent

Substance that loses electrons and is oxidized.

Galvanic Cell

Produces electrical energy spontaneously.

Electrolytic Cell

Requires external energy to drive non-spontaneous reactions.

Electrochemical Cell

Consists of two half-cells and a salt bridge.

Anode

Site of oxidation; electrons are released.

Cathode

Site of reduction; electrons are accepted.

Salt Bridge

Allows ion movement while preventing mixing of solutions.

Half Cell

Consists of an electrode and electrolyte.

Standard Hydrogen Electrode (SHE)

Reference electrode with 0.00 V potential.

Reduction Potential

Ability of a substance to gain electrons.

Potentiometry

Measures voltage to determine ion concentration.

Ion-Selective Electrode (ISE)

Measures specific ion activity.

Direct ISE

Measurement without dilution.

Indirect ISE

Measurement with dilution.

pH Meter

Measures hydrogen ion concentration.

Indicator Electrode

Responds to analyte ions (H+).

Reference Electrode

Provides stable constant voltage.

Glass Electrode

Selective membrane for H+ ions.

Silver/Silver Chloride Electrode

Common reference electrode.

Calomel Electrode

Another type of reference electrode.

Liquid Junction

Region where reference and sample solutions meet.

Coulometry

Measures electricity at fixed potential; follows Faraday’s law.

Amperometry

Measures current from redox reactions.

Voltammetry

Measures current as voltage is applied.

Anodic Stripping Voltammetry

Used for detection of metals like lead and iron.

Applications of Coulometry

Chloride determination.

Interferences in Coulometry

Bromide, cyanide, cystine.

Applications of Amperometry

pO2, glucose, chloride, peroxidase tests.

True

Galvanic cells produce energy spontaneously.

False

Electrolytic cells produce energy without external power.

True

Oxidation occurs at the anode.

False

Reduction occurs at the anode.

True

Reduction occurs at the cathode.

False

Cathode is site of oxidation.

True

Electric current is measured in amperes.

False

Electric current is measured in volts.

True

Electric potential is measured in volts.

False

Electric potential is measured in amperes.

True

SHE has a value of 0.00 V.

False

SHE value is measured experimentally.

True

Salt bridge allows ion flow.

False

Salt bridge mixes the solutions.

True

Potentiometry measures voltage.

False

Potentiometry measures current.

True

Coulometry follows Faraday’s law.

False

Coulometry ignores electron transfer.

True

Amperometry measures current.

False

Amperometry measures only voltage.

True

Voltammetry measures current after applying voltage.

False

Voltammetry measures resistance only.

Spectrometry

Measurement of light interaction with matter

Spectrophotometry

Technique that measures light absorbed or transmitted by a solution

Transmitted Light

Light that passes through a solution

Incident Light

Light that initially strikes a sample

Percent Transmittance

Ratio of transmitted light to incident light multiplied by 100

Absorbance

Amount of light absorbed by a sample

Beer’s Law

States that absorbance is directly proportional to concentration

Molar Absorptivity

Constant that indicates how strongly a substance absorbs light

Path Length

Distance light travels through a sample

Calibration Curve

Graph of absorbance versus concentration

Visible Light Spectrum

Range of light visible to the human eye

Absorptimetry

Measurement based on absorption of radiant energy

Colorimetry

Measurement using visible light

Monochromator

Device that isolates specific wavelengths of light

Bandpass

Range of wavelengths transmitted at more than 50% intensity

Colored Glass Filter

Filter that passes broad wavelength ranges

Interference Filter

Filter that produces narrow wavelength bands

Prism Monochromator

Uses refraction to separate light into spectrum

Diffraction Grating

Uses diffraction to disperse light into wavelengths

Cuvette

Container that holds the sample

Glass Cuvette

Used for visible light measurements

Quartz Cuvette

Used for UV measurements

Photodetector

Device that converts light into electrical signal

Photocell

Simple detector that generates its own current

Phototube

Detector requiring external voltage

Photomultiplier Tube

Highly sensitive detector that amplifies signal

Photodiode

Semiconductor detector with fast response

Photodiode Array

Multiple photodiodes detecting different wavelengths

Single Beam Instrument

Uses one light path

Double Beam Instrument

Splits light into sample and reference

Stray Light

Unwanted light reaching the detector

Wavelength Accuracy

Correctness of selected wavelength

Linearity

Ability to produce proportional results

Light Source

Provides radiant energy for measurement

Tungsten Lamp

Light source for visible range

Deuterium Lamp

Light source for UV range

Mercury Arc Lamp

Produces sharp emission lines

Didymium Filter

Used to check wavelength accuracy

Holmium Oxide Filter

Standard for wavelength calibration

True

Beer’s Law states that absorbance is directly proportional to concentration

False

Absorbance decreases when concentration increases

True

100% transmittance means no light is absorbed