Quiz 2 Flashcards
Ox / Redox pneumonic
Oil Rig
Oxidation is loss
Reduction is gain
Oxidizing agent
gains electrons from an ox/redox reaction. The oxidizing agent is reduced
Reduction agent
provides e- for a redox reaction. The reducing agent is oxidized
Primary cells
Non-reversible
Non-rechargeable
Considered a “dry” cell
comes from reactions that are generally not reversible
Secondary Cell
Reversible and Rechargeable because reactants remain on electrode surface
Reversal of e- flow lets reactants be regenerated by reverse reaction
“Wet” cell
recyclable like a Li-on battery
Spontaneous vs non-spontaneous
Spontaneous (such as a galvanic cell) has a negative delta G for the reaction.
Non-spontaneous are driven by application of current. Positive delta G (occurs in electrolytic cell)
Balancing redox reactions
- write the equation
- What is oxidized, what is reduced? write the half reactions
- balance the halves, use water to balance O, H+ to balance hydrogen
- balance with electrons to correct for charge
- add the half reactions
Galvanic cell diagram
anode (left) is oxidized providing electron flow right to the cathode. potassium sulfate salt bridge connects the jars under the circuit with electron flow
why is the salt bridge needed
salt bridge allows for flow of ions from cathode to anode
standard conditions
1.0m concentration
1 bar, 1.01 atm pressure
standard states
298K
When determining standard reduction potentials…
remember that you may need to flip a charge for the reverse reaction
Latimer Diagrams
most oxidized species is on the left
Disproportionation
element is simultaneously oxidized and reduced
Comproportionation
element at two oxidation states is reduced to one
Frost diagram
the most stable oxidation state is the lowest point on the diagram
What species will disproportionate on a frost diagram?
those on a convex curve (top of curve less stable)
what species will comproportionate on a frost diagram?
those on a concave curve (bottom [cave in] more stable, two will try to take this form)
What is the strongest oxidizer in a frost diagram?
top left position
what is the strongest reducing agent in a frost diagram?
top right position
Battery set up
Left jar: anode (oxidation) an ox! Fe --> Fe2+ +2e- Right jar: cathode (reduction) red cat! Cu2+ +2e- --> Cu Electron flow: anode to cathode, left to right Ion flow:
Size in the anode starts to deteriorate, size in cathode has sick gains
Cell notation
Anode solid | Anode aqueous || Cathode aqueous | Cathode Solid
Ecell =
E cathode - E anode
In equation form, what is different between the anode and the cathode
the anode has the e- on the right (oxidation)
the cathode has the e- on the left (reduction)
3 cell types
simple cubic: spheres touching on axis (bad orange stack, space unfilled)
Face centered cubic: bad orange stack with support (space filled)
Body centered cubic: best orange stack (all spheres lined up on radius)
Solids organization tree
Pure solids
- Amorphous
- Crystalline
- – covalent
- – Ionic
- – Molecular
ABA, CBA
hexagonal closest packing
- hex, tri, hex
cubic closest packing
hex, tri, tri, hex
Holes
Octahedral - three spheres offset by three opposite oriented spheres lives a hex Tetrahedral - three spheres leaves a triangle Cubic - space left by bad orange packing
polymorphism
the ability of a solid to have multiple configurations in the solid state (chocolate and bloom, carbon allotrope)
Ketelaar triangle
used to show composition of alloys
may occasionally result in Zintl phase in which two alloys are unaligned: very brittle
Alloy types
pure
substitutional: a similar sized sub for parts of metal
interstitial: fill out open space with smaller metal
hybrid
Born - Haber Cycle
Energy for sublimation = +
Ionization Energy 1 = +
Dissociation energy(separate a diatomic, only need 1 so half) = +
Electron Affinity energy = -
Lattice Energy from bond formation = large -
net result negative = favored reaction
Which is larger: anion or cation
Anions tend to be larger
Which is negatively charged: anion or cation
anion
frost diagram axis
y axis is delta G
x axis is oxidation number
slope = Ecell
N type vs P type
N type is donor band. Elements from group five can donate an extra electron to reduce band gap
P type is an acceptor band and can receive electrons density to bridge the band gap (III)
both are doped(extrinsic) semi-conductors
band gap types
metal: partial overlap
semi-metal: direct contact between full and empty band
insulator: large gap
silicate structures
isolated tetrahedral single chains double chains sheet framework
zeolite composition
Si, Al, O
Organosilicones
chemically inert
heat stable
water repellant
metal characteristics
outer electrons are able to wander through
electric fields move them through
free electrons make for good transfer of energy
