Electrochemistry

Question 1

electromotive force

Answer 1

Ecell = Ecathode - Eanode

difference between standard production potential of the reaction at the anode and the cathode

work that is done per unit of charge or joules of work per coulomb of charge

Question 2

standard reduction potential

Answer 2

potential (in volts) required to reduce the compound

the more negative something is, the less likely it will be reduced

Question 3

electrolytic cells

Answer 3

standard reduction potential is negative
non spontaneous reaction
charging –> external potential is applied to force oxidation-reduction reaction

Question 4

galvanic cell

Answer 4

electrochemical cell that converts chemical energy into electrical energy via an oxidation reduction reaction

occurs spontaneously
Ecell = +

Question 5

concentration cell

Answer 5

type of galvanic cell in which ions diffuse across a membrane and create a potential

standard reduction potential is postive

Question 6

fuel cell

Answer 6

type of galvanic cell whose reactants are continuously supplied at the anode and cathode, and whose products are removed from the system

Ecell = +

Question 7

electroplating

Answer 7

deposition of solids from electrolysis

involves reduction of a metal ion to a metal solid at the cathode of an electrolytic cell

Question 8

calculating electroplating

Answer 8

It/nF

IT is Not Fun

Q=IT
charge in Coulombs - current (amps) x time (seconds)

n = moles
F= Farday's constant = 96,500C/mole e-

Question 9

To charge a battery what must the external potential be?

Answer 9

a greater voltage than what is produced by a discharging battery

this is because circuits have an internal resistance that will deplete a portion of the applied voltage so the reverse reaction will require more of an applied potential to drive the reaction in a non-spontaneous direction

Question 10

What charge does the applied potential produce?

Answer 10

a positive charge because the potential must overcome the negative potential of the reverse reaction

Question 11

when the products of the concentration of ions in a solution is equal to Ksp

Answer 11

equilibrium

dissolution and precipitate rates are equal

Question 12

Why does a precipitate form?

Answer 12

when the concentration of ions is larger than the Ksp value

[Mg][OH]^2 > Ksp

therefore there is extra stuff that won’t be dissolved

Question 13

what causes corrosion to occur more quickly?

Answer 13

metals in the presence of anions with which they form soluble salts will corrode more quickly than they will in pure water

Question 14

solubility

Answer 14

based on number of moles that can dissolve in a given volume of solvent

Question 15

Faraday’s constant

Answer 15

96,500 C/moles electrons

Question 16

Gibbs free energy in galvanic cell equaiton

Answer 16

delta G = -nFE

F=faraday’s constant
e=cell potential = voltage

Question 17

standard cell potential equation

Answer 17

E= - 0.0257lnK/n

or

E = 0.06logK/n

Question 18

Nernst Equation

Answer 18

E = E0 + 0.0257lnQ/n

or

E = E0 + 0.06logQ/n

Question 19

If the ETC is a spontaneous process, what must be true about the redox reactions within each of the four complexes?

Answer 19

The E’cell value increases as electrons are passed from one carrier to the next

because O2 is the final reducer, it needs to have a large E’cell (because the more positive the Ecell, the more the complex wants to accept electrons)

Question 20

catabolism

Answer 20

breaking down biological fuel molecules like carbohydrates, lipids, and proteins into smaller molecules

oxidative process that releases energy –> becomes reduced itself

ex: NAD+–>NADH

NADH is a product of catabolic oxidation

Question 21

electron transduction

Answer 21

energy travels from the passing of electrons from donor (NADH/FADH2) to acceptors (ETC –> O2)

Question 22

anabolism

Answer 22

requires energy to build more complex things

reduces things to become oxidized itself

Question 23

reference electrode

Answer 23

has a known electric potential and standard concentration of reacting species

Question 24

concentration cell

Answer 24

both electrodes contain the same chemical species

Question 25

Polarization

Answer 25

unequal distribution of electron density in polarized molecules that induces a dipole