Batteries

Question 1

Lead-acid battery reaction

Answer 1

Pb (s) + PbO2 (s) + 4H+ (aq) + 2 SO4(2-)(aq) –> 2PbSO4 (s) + 2H2O (l) (half-reactions on chart)

Question 2

Lead-acid battery components + model

Answer 2

Solid grids alternating from each other in H2SO4 (aq) solution, cathode made of solid PbO2 and anode made of spongy lead Pb (s).

Question 3

Lead-acid battery initial charging reaction

Answer 3

Overall: Pb(s) + 2H2O(l) –> PbO2(s) + 2H2(g)
(cathode reaction reduces H+ ions because Pb(s) cannot be reduced

Question 4

Lead-acid battery initial components + model

Answer 4

Lead grids alternating each other (anode and cathode) in H2SO4 solution

Question 5

Voltaic cells flow of electrons

Answer 5

Anode to cathode

Question 6

Voltaic cells flow of ions

Answer 6

cations to cathode, anions to anode

Question 7

Voltaic cell components + model

Answer 7

Anode (solid in anode solution), cathode (solid in cathode solution), salt bridge, wire connecting cathode and anode to voltmeter

Question 8

Voltaic cell standard notation

Answer 8

|Anode|Anode solution||Cathode solution|Cathode

Question 9

Standard Hydrogen Electrode (SHE) purpose

Answer 9

Used to determine the standard cell potential of different substances

Question 10

SHE reaction + model

Answer 10

2H+(aq) + 2e- –> H2(g) (oxidation of H2 and reduction of H+ occur on surface of Pt electrode)

Question 11

Alkaline battery reaction

Answer 11

Zn + 2MnO2 + 2H2O –> Zn(OH)2 + 2MnO(OH)
Zn is oxidized, Mn is reduced

Question 12

Alkaline battery components + model

Answer 12

May contain several voltaic cells so not rechargeable
Circular in shape, contains cathode on top (MnO2 + graphite) and anode on bottom (Zn + KOH), gasket, separator, KOH is electrolyte

Question 13

Nickel-cadmium batteries

Answer 13

rechargeable batteries, spontaneous reaction of reduction of nickel and oxidation of cadmium

Question 14

Nickel-cadmium batteries reaction

Answer 14

2NiO(OH) + Cd + H2O –> 2Ni(OH)2 + Cd(OH)2

Question 15

Lithium-ion batteries

Answer 15

Rechargeable
Spontaneous reduction of Co and oxidation of lithium
high voltage but flammable

Question 16

Lithium-ion batteries reaction

Answer 16

Li (in graphite) + CoO2 –> graphite + LiCoO2

Question 17

Fuel cells

Answer 17

Uses redox reactions between organic combustible fuels and O2 (g) to generate electricity
Voltaic cell, used in cars in H2/O2 fuel cells

Question 18

Hydrogen fuel cell reaction + model

Answer 18

2H2 + O2 –> 2H2O
(H2 oxidized to H+ first, then reacts w O2 to form water)

Question 19

Rust reaction

Answer 19

4Fe + 3O2 –> 2Fe2O3

Question 20

Rust reaction components

Answer 20

Anode: Fe (reactive anode, is getting oxidized)
Cathode: Fe2O3 (self-reducing)

Question 21

Rust reaction characteristics

Answer 21

Self-accelerating, sped up by presence of electrolytes like NaCl, slowed down by painting Fe or covering with sacrificial anodes

Question 22

Electrolytic cell

Answer 22

Nonspontaneous reaction run by outside source (electrolysis), uses electricity to split up a molten substance (ex. NaCl)

Question 23

Electrolytic cell sample reaction + model

Answer 23

NaCl (molten) –> Na (l) + 1/2Cl2 (g)