Question | Answer |
Electrochemistry | the area of chemistry that deals with the interconversion of electrical energy and chemical energy |
Elecrochemistry involves: | 1. using electricity to maker chemical reactions and 2. using chemical reactions to produce electricity |
electrochemical processes are? | oxidation- reduction reactions in which energy released by a spontaneous reactions is converted to electricity and electrical energy is used to cause a non spontaneous reaction to occur |
oxidation | is a half reaction in which you lose e- |
reduction | is a half reaction in which you gain e- |
oxidation numbers | the charge an atom would have in a molecule (or in an ionic compound) if electrons were completely transferred |
Free elements in an uncombined state have an oxidation number of? | zero |
in mono-atomic ions the oxidation number is? | equal to the charge on the ion |
The oxidation number of oxygen is usually? | -2. In H2O2 and O2(2-) it -1. |
the oxidation number of hydrogen is | +1, except when it is bonded to metals in binary compounds, it is -1. |
The oxidation number of group 1A metals is: | +1 |
The oxidation number of group IIA metals is: | +2 |
Fluorine's oxidation number is always: | -1 |
The sum of the oxidation numbers of all the atoms in a molecule is equal to? | the charge on the molecule or atom. |
Anode | the electrode at which oxidation occurs, it positive |
Cathode | the electrode at which reduction occurs, it negative |
Half-cell reactions | redox reactions |
voltometer | measures the difference in electrical potential between the anode and cathode |
Galvanic Cells | an apparatus for generating electricity through the use of a spontaneous reaction |
What does the subscript "o" denote? | Standard state condition |
Cell voltage | the difference in electrical potential between the anode and the cathode |
Double lines denote? | a salt bridge |
Standard reduction potential (E0)- | is the voltage associated with a reduction reaction at an electrode when all solutes are 1M and all gases are at 1 atm |
Standard emf (E0Cell) | E0cell= E0cathode- E0anode |
The more positive E0 | the greater the tendency for the substance to be reduced |
are half cell reactions reversible? | yes |
the sign of E0 changes when? | the reaction is reversed |
Changing the stoichiometric coefficients of a half-cell reaction does what? | It does not change the value of E0 |
Energy (joules)= | change(coulomb) x voltage(volts) |
Faraday constant (F)= | the charge of one mole of electrons |
ΔG is negative K>1 E0cell= | positive, favors the formation of products |
ΔG is positive K<1 E0cell= | negative, favors the formation of reactants |
Concentration cell- | a galvanic cell from two half-cells composed of the same material but differing in ion concentrations |
Membrane potential- | is the electrical potential that exists across the membrane of various kinds of cells including muscle and nerve cells |
Nerst equations | E=-(0.0257V/n) lnQ |
Battery- | a galvanic cell, or series of combined galvanic cells, that can be used as a source of direct electrical current at a constant voltage. Are self contained and require no salt bridge. |
Leclanche' cell | the most common battery, with no fluid component |
Mercury Battery | used in medicine, provides consistent voltage |
Lead storage battery | used in automobiles, consists of 6 identical cells joined in a series, and is rechargeable |
Solid state Lithium battery | Rechargeable, long-lasting, very light. It is used in cell phones, cameras, and laptops. |
Fuel Cell- | is an electrochemical cell that requires a continuous supply of reactants to keep functioning. |
Corrosion- | the deterioration of metals bu an electrochemical process |
Passivation- | process by which the surface of iron metal is made inactive by treating it with a strong oxidizing agent to for a thin oxide layer |
Cathodic protection- | process in which a metal that is to be protected from erosion is made the cathode in that amounts to a galvanic cell |
electrolytic cell- | an apparatus for carrying out electrolysis |
Electrolysis- | the process on which electrical energy is used top cause a non-spontaneous chemical reaction to occur |
overvoltage- | the difference between the electrode potential and the actual voltage required to cause electrolysis |