ELECTROCHEMISTRY Flashcards
It is a weak oxidizing agent used primarily for the determination of strong reductants.
Iodine
It is a reagent decomposes on standing, and has been applied to the determination of water in numerous types of samples.
Karl Fischer reagent
T OR F: Cathode is the electrode at which an oxidation takes place
False
Is capable of making electrical energy through using the chemical energy that came from chemical reactions and chemical energy by using electrical energy as its power source.
Electrochemical cell
This is an external source of electrical energy for operation
Electrolytic cell
What is called a change from the color of the oxidized form of the indicator to the color of the reduced form requires a change of about 100 in the ratio of a reactant concentrations?
General Redox Indicator
Italian physicist, was the inventor of the first battery, the so-called voltaic pile.
Alessandro Volta
Consist of two conductors called electrodes immersed in an electrolyte solution?
Electrochemical Cell
Electrode at which an oxidation takes place
Anode
What is the best known specific indicator which forms a dark blue complex with triiodide ion?
Starch
Is the electrode potential when the activities of the
reactants and products are all unity
Standard Electrode Potential
It occurs when the red color of the iron(III)/thiocyanate complex disappears as a result of the significant decrease in the iron(III) concentration at the equivalence point.
END POINT
What are the two common reductants?
Iron (II)
Thiosulfate ion
It is substance that change color on being oxidized or reduced.
General Redox Indicators
An alternative to filtration is the use of _______. Wherein, the finely divided metal is held in a vertical glass tube through which the solution is drawn under a mild vacuum.
REDUCTOR
When _____ donates a proton, it became conjugate base capable of accepting a proton.
Acid
Electrochemical cell is composed of two conductors called?
electrodes
Electrons are transferred From one reactant to another
Oxidation/Reduction Reaction - AKA Redox Reaction
Has strong affinity to electrons (electrons acceptor)
Oxidizing Agent(Oxidant)
Donates Electron to other species
Reducing Agent(Reductant)
Oxidation/reduction reaction is analogous to ______ of acid/base reaction
Bronsted – Lowry Concept
When acid donates a proton, it became conjugate base capable of ______
accepting a proton.
When a reducing agent donates an electron, it becomes an oxidizing agent that can ______
accept an electron
Two Ways in Carrying Out an Oxidation/ Reduction Reaction
- direct contact in suitable container
- electrochemical cell
piece of copper is immersed in a silver nitrate solution
Silver Tree Experiment
widely used in electrochemistry to prevent mixing of the contents of the two electrolyte solutions making up electrochemical cells
Salt Bridge
is the electrode at which reduction occurs Cathodic Reactions.
Cathode
is the electrode at which an oxidation takes place Anodic Reactions
Anode
Store electrical Energy
Galvanic (Voltaic) cells
are usually made from several such cells connected in series to produce higher voltages than a single cell can produce.
Batteries
Italian physicist, was the inventor of the first battery, the so-called voltaic pile.
Alessandro Volta
Reactions at the two electrodes in such cells tend to proceed spontaneously and produce a flow of electrons from the anode to the cathode via an ____
external conductor
one of the earliest galvanic cells to find widespread practical application
used in the mid-1800s to power telegraphic communication systems
The Daniell Gravity Cell
Is the phase boundary between an electrode and its solution
Interface
Is a reference state that allows us to obtain relative values of such thermodynamic quantities as free energy, activity, enthalpy, and entropy.
Standard State
the standard state has the properties of an ideal gas but at one atmosphere pressure
For Gases
the standard states are real states and are the pure substances at a specified temperature and pressure
For Pure Liquid and Solvents
the standard state is a hypothetical state that has the properties of an infinitely dilute solute but at unit concentration (molar or molal concentration, or mole fraction)
For Solutes in Dilute Solution
the standard state is a real state and is the pure solid in its most stable crystalline form
For Solid
Used as the universal reference electrode
It is easy to conduct, reversible and highly reproducible
Typically a Gas Electrode
SHE(Standard Hydrogen Electrode) AKA Normal Hydrogen Electrode(NHE)
Is the potential of a cell in which the electrode in question is the right-hand electrode and the standard hydrogen electrode is the left-hand electrode
Electrode Potential
is an important physical constant that provides quantitative information regarding the driving force for a half-cell reaction.
standard electrode potential
LIMITATIONS TO THE USE OF SEP
Use of Concentration Instead of Activities
Effects of Other Equilibria
Formal Potentials
reacts rapidly and reversibly, its color change is pronounced, and its solutions are stable and easily prepared
Ferroin
the color changes of true redox indicators are largely independent of the chemical nature of the analyte and titrant and depend instead on the changes in the electrode potential of the system that occur as the titration progresses
Specific Indicators
is another specific indicator which may be used in the titration of iron(III) with solutions of titanium(III) sulfate.
Potassium Thiocyanate
7 Auxiliary Reducing Reagents (ZACaLiN C Silver)
Zinc
Aluminum
Cadmium
Lead
Nickel
Copper
Silver (in the presence of Chloride ion)
An alternative to filtration is the use of a _____
reductor
has a diameter of about 2 cm and holds a 40- to 50-cm column of amalgamated zinc. Amalgamation is accomplished by allowing zinc granules to stand briefly in a solution of mercury(II) chloride
Jones reductor
Auxiliary Oxidizing Reagents
Sodium Bismuthate (NaBiO3 )
Ammonium Peroxydisulfate (NH4 )2S2O8
Sodium Peroxide and Hydrogen Peroxide
powerful oxidizing agent capable of converting manganese(II) quantitatively to permanganate ion
Sodium Bismuthate (NaBiO3 )
is a sparingly soluble solid with a formula that is usually written as oxidations are performed by suspending the bismuthate in the analyte solution and boiling for a brief period
bismuth salt
In acidic solution, it converts chromium(III) to dichromate, cerium(III) to cerium(IV), and manganese(II) to permanganate.
Ammonium Peroxydisulfate
is a convenient oxidizing agent either as the solid sodium salt or as a dilute solution of the acid
Sodium Peroxide and Hydrogen Peroxide
easily prepared from iron(II) ammonium sulfate (Mohr’s salt), or from the closely related iron(II) ethylenediamine sulfate (Oesper’s salt).
Iron(II) Solutions
is a moderately strong reducing agent that has been widely used to determine oxidizing agents by an indirect procedure in which iodine is an intermediate.
Sodium Thiosulfate Ions
are indefinitely stable, can be boiled without decomposition, and do not react with hydrochloric acid.
Dichromate ion is reduced to green chromium(III) ion.
Potassium dichromate
This ion cannot be used with hydrochloric acid solutions unless special precautions are taken to prevent the slow oxidation of chloride ion that leads to overconsumption of the standard reagent?
Permanganate ion
