Electrochemistry

Question 0

Electrochemical cell

Answer 0

A device that stages redox reaction that either results in or is driven by an electric current

Question 1

Electric current

Answer 1

The flow of an electric charge through a substance

Question 2

Voltaic cell

Answer 2

An electrochemical cell that produces an electric current from a spontaneous chemical reaction

Question 3

Electrolytic cell

Answer 3

Type of electrochemical cell that consumes current to drive a non-spontaneous chemical reaction

Question 4

Half-cell

Answer 4

The first of two reactions in an electrochemical cell

Question 5

Electrodes

Answer 5

Conductive surfaces through which electrons can either enter or leave the half sells

Question 6

Ampes (A)

Answer 6

Unit of measure for an electric current

1 amp = 1 culoumb

Question 7

Electrical potential difference

Answer 7

The difference in potential energy (joules) per unit of charge

Drives the electric current

Question 8

Volt (v)

Answer 8

Unit of measure for potential difference

Question 9

Electromotive force

Answer 9

The force that moves electrons through a circiut

Question 10

Cell potential (E sub-‘cell’)

Answer 10

The total voltage between the two cells,

Depends on the relative tendencies of the reactants to undergo oxidation or reduction

Question 11

Standard cell potential

Answer 11

Cell potential for 1M concentration of reactants and products
In a chemical equation

Question 12

Anode

Answer 12

Half-cell in which oxidation occurs

Question 13

Cathode

Answer 13

Half-cell that undergoes reduction

Question 14

Salt-bridge

Answer 14

U-shaped tube that provides the electrolytes to both half-cells in the electrochemical cell

Question 15

Standard electrode potential

Answer 15

The individual potential of the electrode in each half-cell

Question 16

Standard hydrogen electode

Answer 16

The half-cell electrode that is normally chosen to have a potential of zero

Question 17

Predicting current direction

Answer 17

From the anode to the cathode, always

Question 18

Standard electrode potential

Answer 18

The individual potential of the electrode in a half cell

Cell= (.0592/n)*log K

Question 19

Faradays constant

Answer 19

96,485

Question 20

Gibbs free energy

Answer 20

Later used to calculate either temperature, enthalpy(H: energy sum), or entropy(S- number microstates)
ΔG=ΔH-T(ΔS)

Question 21

Nearst equation

Answer 21

(Cell potential-(.0592/n) logQ

Question 22

Dry cell batteries

Answer 22

Electric cell that does not contain high volumes of liquid

Question 23

Electrolysis

Answer 23

The process through which an electric current drives a non-spontaneous reaction

Question 24

Magnetic moment

Answer 24

Magnetic quantity that describes the force that a magnet can exert on electric currents and the torque the magnetic field will exert on it

Question 25

Battery Types

Answer 25

``` Lead-Acid Dry-cell (Alkaline and Zinc) Nickel-Cadium (NiCad) Nickel-Metal Hydride (NiMH) Lithium Ion J ```

Question 26

Zinc Battery Reaction mechanism

Answer 26

``` Do not contain high volumes of liquid Anode Zn(s)→Zn+2(aq)+2e- Cathode 2MnO2(s)+2NH4+(aq)+2e-→Mn2O3(s)+2NH3(g)+H2O(l) ```

Question 27

Alkaline Battery reaction mechanism

Answer 27

``` Slightly different reaction from standard zinc batteries Anode Zn(s)+2OH-(aq)→Zn(OH)2(s)+2e- Cathode 2MnO2(s)+2H2O(l)+2e-→Mn2O3(s)+2OH-(aq) ``` Overall Reaction Zn(s)+2MnO2(s)+2H2O(l)→Zn(OH)2(s)+2MnO(OH)(s)

Question 28

Nickel-Cadmium Battery Reaction mechanism

Answer 28

``` Anode Cd(s)+2OH-(aq)→Cd(OH)2(s)+2e- Cathode 2NiO(OH)(s)+2H2O(l)+2e-→2Ni(OH)2(s)+2OH-(aq) ```

Question 29

Nickel-Metal Hydride Battery reaction mechanism

Answer 29

Anode M,H(s)+OH-(aq)→M,(s)+H2O(l)+e- Where 'M,' indicates a metal alloy Cathode NiO(OH)(s)+H2O(l)+e-→Ni(OH)2(s)+OH-(aq)

Question 30

Lithium Ion Battery mechanisms of action

Answer 30

Lithium ions naturally travel from graphite to a (transition metal)-oxide, forming Lithium (transition metal)-oxide and producing a charge The recharge uses an electric current to strip the lithium ions from the (transition-metal)oxide

Question 31

Hydrogen Fuel cell

Answer 31

Hydrogen gas and a hydroxide solution are supplied to the cell and react, producing water and giving off 4 electrons. These electrons run up the anode, are supplied to the electrical circuit, and re-enter the fuel cell through the cathode where they drive the reaction between oxygen gas and water producing 4OH- ions

Question 32

Alcohol battery reaction mechanism

Answer 32

Ethyl-alcohol (CH3CH2OH) gas reacts with a OH- solution in the anode,producing acetic acid gas (HC2H3O2), liquid water, and giving off 4 electrons which run through the circuit and back to the cathode to drive the reaction between oxygen gas and the water to re-form the OH- solution

Question 33

Electrolysis of water

Answer 33

In an anode: 2H2O(l)→O2(g)+4H(aq)+4e- Or in a cathode: 2H2O(l)+2e-→H2(g)+2OH-(aq)

Question 34

Gibbs free energy from cell potential

Answer 34

ΔG=-n*F*E.cell

Question 35

Cell potential from Gibbs free energy

Answer 35

E.cell=ΔG/(-n*F)

Question 36

Cell potential from equilibrium constant

Answer 36

E.cell=(0.0592/n)*log(K)

Question 37

Equilibrium constant (K) from the cell potential

Answer 37

log(K)=E.cell/(0.0592/n)

Question 38

Gibbs free energy from equilibrium constant K

Answer 38

ΔG=-R*T*ln(K)

Question 39

Equilibrium constant (K) from Gibbs free energy

Answer 39

Ln(K)=ΔG/(-R*T)

Question 40

Power diffraction

Answer 40

Technique using x-ray, neutron, or electron diffraction on power or microstalline samples for structural characterization of materials