Electrochemistry

Question 1

redox reaction

Answer 1

oxidation-reduction reaction
e-s transferred from one atom to another
oxidized = loses e-s
reduced = gains e-s

Question 2

oxidation states

Answer 2

possible charge values that an atom may hold within a molecule
must add up to the charge on molecule or ion

Question 3

oxidation state of 0

Answer 3

atoms in their elemental form

Question 4

oxidation state of -1

Answer 4

fluorine

Question 5

oxidation state of +1

Answer 5

hydrogen (except when bonded to a metal like NaH, then -1)

Question 6

oxidation state of -2

Answer 6

oxygen (except when it is in a peroxide like H2O2, then -1)

Question 7

reducing agent/reductant

Answer 7

compound giving electrons, oxidized

Question 8

oxidizing agent/oxidant

Answer 8

compound accepting electrons, reduced

Question 9

electric potential (E)

Answer 9

associated with any redox reaction because e-s are transferred

Question 10

half reaction

Answer 10

each component of redox reaction

one possible potential for any given half reaction

Question 11

reduction potentials

Answer 11

how half reactions are usually written
sign reversed for the oxidation potential
more positive - stronger oxidizing agents, easily reduced
more negative - stronger reducing agents, easily oxidized

Question 12

standard hydrogen electrode half reaction

Answer 12

2H+ + 2e- –> H2

E = 0.00V

Question 13

galvanic cell/voltaic cell

Answer 13

uses the electric potential between phases to generate a current of e-s from one phase to another in a conversion of chemical energy to electric energy

Question 14

salt bridge

Answer 14

phase that is impermeable to e-s in a galvanic cell

ionic conductor carrying current in form of ions

Question 15

terminals or galvanic cell

Answer 15

electronic conductors (metal wires) 
emf is electric potential difference between terminals

Question 16

2 electrodes of galvanic cell

Answer 16

anode (-) and cathode (+)
oxidation at anode
reduction at cathode 
e-s flow to cathode 
current flows cathode --> anode

Question 17

cell potential (E) / electromotive force (emf)

Answer 17

potential difference between the terminals )when they are not connected

Question 18

positive cell potential indicates a ……. (with equation)

Answer 18

spontaneous reaction
(delta)G = -nFE
n = number of e-s transferred

Question 19

(delta)G and (delta)G prime equation

Answer 19

(delta)G = (delta)G(prime) + RTln(Q)
Q = the reaction quotient

Question 20

equilibrium, (delta)G(prime) =

Answer 20

-RTln(K)
varies with temp
K= 1, (delta)G(prime) = 0
K >1, (delta)G(prime) 0

Question 21

concentration cell

Answer 21

limited form of a galvanic cell with a reduction half reaction taking place in one half cell and the exact reverse of that half reaction in the other half cell
*type of galvanic cell, never at standard conditions

Question 22

electrolytic cell

Answer 22

power source across the resistance of galvanic cell, force cell to run backwards
will have negative emf
cathode (-), anode (+)
reduction at cathode and oxidation at anode
used for metal plating and purifying metals