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57 terms

Chemistry 621A (Final Exam Prep)

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Electrochemical process
the conversion of chemical energy into electrical energy or electrical energy into chemical energy; all electrochemical processes involve redox reactions
Electrochemical Cell
Any device that converts chemical energy into electrical energy or electrical energy into chemical energy
Voltaic Cell
An electrochemical cell used to convert chemical energy into electrical energy; the energy is produced by a spontaneous redox reaction
Half-Cell
the part of a voltaic cell in which either oxidation or reduction occurs; it consists of a single electrode immersed in a solution of its ions
Salt Bridge
a tube containing a strong electrolyte used to separate the half-cells in a voltaic cell; it allows the passage of ions from one half-cell to the other but prevents the solutions from mixing completely
Electrode
A conductor in a circuit that carries electrons to or from a substance other than a metal
Anode
the electrode at which oxidation occurs
Cathode
the electrode at which reduction occurs
Dry Cell
a commercial voltaic cell in which the electrolyte is a moist paste. Example - Flashlight batteries
Battery
A group of voltaic cells that are connected to one another
Fuel cell
a voltaic cell that does not need to be recharged; the fuel is oxidized to produce a continuous supply of electrical energy
Electrical potential
the ability of a voltaic cell to produce an electrical current
Reduction Potential
a measure of the tendency of a given half-reaction to occur as a reduction (gain of electrons) in an electrochemical cell
Cell Potential
the difference between the reduction potentials of two half cells
Standard Cell Potential
The measured cell potential when an ion concentration in the half cells are 1.00M at 1ATM of pressure and 25C. (E cell)
Standard Hydrogen Electrode
An arbitrary reference electrode (half-cell) used with another electrode (half-cell) to measure the standard reduction potential of that cell; the standard reduction potential of a hydrogen electrode is assigned a value of 0.00V
Electrolysis
A process in which electrical energy is used to bring about a chemical change; the electrolysis of water produces hydrogen and oxygen
Electrolyte Cell
An electrochemical cell used to cause a chemical change through the application of electrical energy
Oxidation
A process that involves complete or partial loss of electrons or a gain of oxygen; it results in an increase in the oxidation number of an ion
Oxidation-Reduction Reaction
A reaction that involves the transfer of electrons between reactants
Oxidizing agent
The substance in a redox reaction that accepts electrons; in the reaction, the oxidizing agent is reduced.
Redox Reaction
Another name for an oxidation-reduction reaction
Reducing Agent
the substance in a redox reaction that donates electrons; in the reaction, the reducing agent is oxidized
Reduction
A process that involves a complete or partial gain of electrons or the loss of oxygen; it results in a decrease in the oxidation numbers of an atom.
Oxidation Number
A positive or negative number assigned to an atom to indicate its degree of oxidation or reduction; the oxidation number of an uncombined element is zero
Oxidation-Number-Change Method
A method a balancing a redox equation by comparing the increases and decreases in oxidation numbers.
Monoprotic acids
any acid that contains one ionizable proton (H+ ion); ex: HNO3
Diprotic Acids
acids that contain two ionizable hydrogens (H2SO4)
Triprotic Acid
an acid that has three ionizable protons per molecule, such as phosphoric acid
Conjugate acid
The species produced when a base accepts a hydrogen ion from an acid
Conjugate Base
the particle that remains when an acid has donated a hydrogen ion
Conjugate Acid-Base Pair
consists of two substances related by the loss or gain of a single hydrogen ion
Hydronium Ion
an ion consisting of a proton combined with a molecule of water; H3O+
Amphoteric
having characteristics of both an acid and a base and capable of reacting as either
Lewis Acid
an atom, ion, or molecule that accepts an electron pair to form a covalent bond
Lewis Base
any substance that can donate a pair of electrons to form a covalent bond
Self-Ionization
a term describing the reaction in which two water molecules react to produce ions
Neutral Solution
an aqueous solution in which the concentrations of H+ and OH- ions are equal; pH = 7
Ion-Product Constant for Water
the product of the concentrations of hydrogen ions and hydroxide ions in water; it is 1 X 10^-14 at 25 degrees C
Acidic Solution
Any water solution that has more hydrogen ions (H+) than hydroxide ions (OH-); pH is less than 7
Basic Solution
any solution in which the hydroxide-ion concentration is greater than the hydrogen-ion concentration
Alkaline Solution
has a ph higher than 7; a basic solution
pH
A measure of hydrogen ion concentration equal to -log [H+] and ranging in value from 0 to 14.
Strong Acid
an acid that is completely or almost completely ionized in aqueous solution
Strong Base
a base that completely dissociates into metal ions and hydroxide ions in aqueous solution
Weak Acid
an acid that is only slightly ionized in aqueous solution
Weak Base
a base that reacts with water to form hydroxide ion and the conjugate acid of the base
Acid dissociation constant (Ka)
the ratio of the concentration of the dissociated form of an acid to the concentration of the undissociated form
Base dissociation constant (Kb)
the ratio of the concentration of the conjugate acid times the concentration of the hydroxide ion to the concentration of the base
Neutralization Reactions
Reactions in which an acid and a base react in an aqueous solution to produce a salt and water
Equivalence Point
The point during a titration when the number of H+ ions and OH- ions are equal. This is at the middle of the steepest part of the titration curve.
Standard Solution
a solution whose concentration is accurately known used in carrying out a titration
Titration
process in which a solution of known concentration is used to determine the concentration of another solution
End Point
the point in a titration at which an indicator changes color
Salt Hydrolysis
a process in which the cations or anions of a dissociated salt accept hydrogen ions from water or donate hydrogen ions to water
Buffers
weak acids or bases that can react with strong acids or bases to prevent sharp, sudden changes in pH
Buffer Capacity
the amount of acid or base that can be added to a buffer solution before a significant change in pH occurs