Chemistry Electrochemistry

Question 1

___ is the study of the relationships between chemical reactions and electrical energy

Answer 1

electrochemistry

Question 2

___ include spontaneous reactions that produce electrical energy and nonspontaneous reactions that use electrical energy to produce a chemical change

Answer 2

electrochemical reactions

Question 3

There are two types of ___: galvanic cells (also known as voltaic cells) and electrolytic cells

Answer 3

electrochemical cells

Question 4

Spontaneous reactions occur in ___, and nonspontaneous reactions occur in electrolytic cells

Answer 4

galvanic

Question 5

Both reaction types contain electrical conductors known as electrodes, where ___ and reduction occur

Answer 5

oxidation

Question 6

For all electrochemical cells, the ___ where oxidation occurs is called the anode, and the electrode where reduction occurs is called the cathode

Answer 6

electrode

Question 7

___ in an electrochemical cell: AN OX and a RED CAT. The ANode is the site of OXidation; REDuction occurs at the CAThode

Answer 7

electrodes

Question 8

A redox reaction occurring in a ___ has a negative delta G and is therefore a spontaneous reaction

Answer 8

galvanic cell

Question 9

The ___ from galvanic cell reactions is harnessed by placing the oxidation and reduction half-reactions in separate containers called half-cells

Answer 9

energy

Question 10

The half cells are then connected by an apparatus that allows the flow of electrons between the ___, creating a circuit

Answer 10

half-cells

Question 11

A salt bridge contains an inert electrolyte, usually KCL or NH4NO3 whose ions will not react directly with the ___ or the ions in solution

Answer 11

electrodes

Question 12

The inert ions flow from the ___ toward the anode to balance the new ions being created, and the inert cations K+ flow toward the cathode to balance the Cu2+ being deposited onto the cathode. This flow depletes the salt bridge and, along with the finite quantity of Cu2+ in the solution, accounts for the relatively short lifetime of the cell. Note that the cations from the salt bridge flow to the cathode, and the anions flow to the anode; this is where the electrodes get their names from

Answer 12

salt bridge

Question 13

The following rules are used in constructing a ___:
1. The reactants and products are always listed from left to right in the form:
anode | anode solution || cathode solution| cathode
2. A single vertical line indicates a phase boundary
3. A double vertical line indicates the presence of a salt bridge or some other type of barrier

Answer 13

cell diagram

Question 14

A ___ occurring in an electrolytic cell has a positive delta G and is therefore nonspontaneous

Answer 14

redox reaction

Question 15

In electrolysis, ___ is required to induce reaction

Answer 15

electrical energy

Question 16

The anode of an electrolytic cell is considered ___ because it is attached to the positive pole of the battery

Answer 16

positive

Question 17

The ___ of a galvanic cell, on the other hand is considered negative because the spontaneous oxidation reaction that takes place at the galvanic cell’s anode is the original source of that cell’s negative charge (is the source of the electrons

Answer 17

anode

Question 18

Oxidation always takes place at the anode in both types of cells, reduction always takes place at the cathode in both types of cells, and electrons always flow through the wire from the ___ to the cathode

Answer 18

anode

Question 19

___ flow in an electrochemical cell: FAT CAT Electrons flor From Anode To CAThode in all types of electrochemical cells

Answer 19

electron

Question 20

In a ___, charge is spontaneously created as electrons are released by the oxidizing species at the anode. Since this is the source of electrons, the anode of a galvanic cell is considered the negative electrode

Answer 20

galvanic cell

Question 21

The ANode of galvaNic cell is ___ Negative

Answer 21

always

Question 22

In an electrolytic cell, ___ are forced through the cathode, where they encounter the oxidizing agent

Answer 22

electrons

Question 23

The cathode is providing electrons, and thus the cathode of an electrolytic cell is considered the ___ electrode

Answer 23

negative

Question 24

Like in any cell, the ___ attracts cations

Answer 24

cathode

Question 25

The positively charged ___ cations (i.e., those that are protonated at the pH of of the solution) will migrate toward the cathode; negatively charged amino acid anions (i.e., those that are deprotonated at the solution pH) migrate instead toward the anode

Answer 25

amino acid

Question 26

The ___ carried by one mole of electrons can be calculated by multiplying the electron charge (1.6E-19) by Avogrado's number: (1.6E-19)(6.022E23)=96,487 C/mol electrons

Answer 26

charge

Question 27

96487 C/ mol electrons is known as ___ constant

Answer 27

Faraday's

Question 28

i x t = n x F | i = current in amperes, t = time in seconds, n = number of moles of ___, and F = the Faraday constant

Answer 28

electrons

Question 29

The species in a redox reaction that will be oxidized or reduced can be determined from the ___ of each species, defined as the tendency of a species to acquire electrons and be reduced

Answer 29

reduction potential

Question 30

Each chemical species has its own intrinsic ___ potential, the more positive the potential, the greater the tendency to be reduced

Answer 30

reduction

Question 31

A ___ (E degree) means a greater tendency for reduction to occur, while a lower E degree means a greater tendency for oxidation to occur

Answer 31

higher standard reduction potential

Question 32

When two ___ occur in the same system, only one can be a reduction; the half-reaction with the lower reduction potential will occur in reverse as an oxidation

Answer 32

half-reactions

Question 33

Standard reduction potentials are also used to calculate the ___ (emf or E degree sub cell) of a reaction, the difference in potential between two half cells

Answer 33

standard electromotive force

Question 34

The E degree sub cell of a reaction is determined by adding the standard reduction potential of the reduced ___ and the standard oxidation potential of the oxidized species

Answer 34

species

Question 35

___ = E degree sub red + E degree sub ox

Answer 35

E degree sub cell

Question 36

The standard E degree sub cell of a galvanic cell is ___, while the standard E degree sub cell of an electrolytic cell is negative

Answer 36

positive

Question 37

The ___ for determining the spontaneity of a reaction is delta G, Gibbs free energy, a measure of the maximum amount of useful work produced by a chemical reaction

Answer 37

thermodynamic criterion

Question 38

In an electrochemical cell, the work done is dependent on the number of coulombs and the energy available. Thus when standard conditions (25 degrees Celsius, 1 atm pressure, and all solutions at 1 M concentration) are present, delta G and E sub cell are related as follows: delta G = -nFEcell where n is the number of ___ of electrons exchanged, and F is the Faraday constant, 10^5 coulombs per mole Keep in mind that if the Faraday constant is expressed in coulombs (J/V), delta G must be expressed in J, not kJ

Answer 38

moles

Question 39

A ___ has a negative delta G and a positive E sub cell, whereas an electrolytic cell has a positive delta G and a negative E sub cell

Answer 39

galvanic cell

Question 40

delta G = -RTlnK sub eq This relates delta G to K sub eq, When K sub eq >1, products are favored over reactants, the forward ___ is spontaneous, and delta G < 0. When K sub eq < 1, reactants are favored, the reverse reaction is preferred, and delta G > 0. Combining the different equations for delta G gives: nFEdegree sub cell = RTlnK sub eq This relationship shows that when K sub eq > 1, ln K sub eq > 0, and E degree sub cell is positive; thus, the reaction goes forward. When K sub eq < 1, ln K sub eq < 0, and E degree sub cell is negative; thus, the reaction goes in the reverse direction

Answer 40

reaction

Question 41

Nernst equation: E sub cell = E degree sub cell - (RT/nF)(lnQ) Q is the reaction ___ for a given reaction and gives the concentration of reactants and products when the reaction is not at equilibrium

Answer 41

quotient

Question 42

When: aA + bB yields cC + dD the reaction ___ would be: Q = ([C]^c[D]^d)/([A]^a[B]^b) This allows the actual E sub cell to be determined based on the E degree sub cell and reagent concentrations Note that the Nernst equation can be rewritten as E cell = E degree sub cell - (RT/nF)(lnQ) = (RT/nF)(lnK sub eq)-(RT/nF)(lnQ) If Q = 1, as under standard conditions, when all concentrations are 1 M, then lnQ = 0, and the entire last term of the equation disappears

Answer 42

quotient