Mcat Chemistry Lecture 7

Front 1

____ - deals w/ relationship between electricity and chemistry
Or about the transfer of electrons

Back 1

Electrochemistry

Front 2

____ = movement of charge

Back 2

Electricity

Front 3

A reaction where electrons are passed from one atom to another is called a ____ or ____ for short

Back 3

reduction-oxidation reaction
redox reaction

Front 4

The electron acceptor is reduced and the electron donor is oxidized

Back 4

redox reaction

Front 5

Leo the Lion says GER

Back 5

Lose electrons oxidation --- Gain electron reduction

Front 6

Oil Rig --

Back 6

oxidation is loss ---- Reduction is gain

Front 7

____ is a method to keep track of the electrons

Back 7

Oxidation state

Front 8

Oxidation state Rules

Back 8

Rule 1 - atoms in their elemental form have an oxidation state of 0. (ex O2)
Rule 2- Hydrogen is +1 except, when bonded to a metal, when bonded to a metal it is -1
Rule 3 - Oxygen has an oxidation state of -2

Front 9

Other Oxidation state rules -

Back 9

Group 1A elements always have an oxidative state of +1, when in their compounds
Group 2A elements will have an oxidative state of +2, when in their compounds
Aluminum will be +3 in its compounds
Fluorine will be -1 in its compounds
The oxidation states in a compound must sum to the charge on that compound

Front 10

Redox reactions -
2H2 + 02 -> 2H2O
Hydrogen is ____
Oxygen is ____

O2 is the ____
H2 is the ____

Back 10

oxidized, goes from 0 oxidative state to +1
reduced, goes from 0 oxidative state to -2

oxidant (oxidizing agent)
reductant (reducing agent)

Front 11

Oxidation and reduction must always take place ____.

Back 11

together

Front 12

The oxidizing or reducing agents are ____, and what is reduces or oxidized are ____.

Back 12

compounds
atoms

Front 13

Combustion of Methane
CH4 + 2O2 -> CO2 + 2H2O

Carbon is ____
Oxygen is ____

Back 13

oxidized, goes from -4 to +4
reduced, goes from 0 oxidative state to -2

Front 14

____, Does not have to have a positive cell potential
Nor does it need a salt bridge, both electrodes can be in the same solution but Still red cat and an ox but!!! Cathode is ____ and anode is ____.
Used for ____.
Positive ions (cations) move toward the ____
Either plate the item or, make the ____ larger.

Back 14

Electrolytic cells -
negative
positive
electrophoresis
cathode
cathode

Front 15

____ - We have a solutions with an unknown concentration of Sn2+
We measure its ____ against some standard solution
We ____ our Sn solution with a known concentration of Ce4+
Every 2 Ce4+ ions oxidize 1 Sn2+ ion to a Sn4+ ion, as the Sn is oxidized the potential difference against the standard solution changes, this creates the familiar sigmoidal curve at the ____ point the Sn has been completely oxidized so If 10 moles were required to completely oxidize then the solution has originally 5 moles of Sn

Back 15

Redox Titrations
voltage
titrate
equivalence

Front 16

____ is an intensive property

Back 16

Electrochemical potential

Front 17

____ - that means that the potential does not depend on the amount, which means that if you use twice as much the potential is still the same.

Back 17

intensive property

Front 18

Money metals have ____
ex. - ____

Back 18

negative oxidation potentials
Platinum, gold, silver, copper and mercury

Front 19

Negative oxidation means that the oxidation is ____, (makes sense that is why we make money out of them) other ones like to give up electrons that is part of metallic character.

Back 19

nonspontaneous

Front 20

There is no absolute 0 ____ but scientists have assigned the reduction of ____ a 0 potential.

Back 20

electrochemical potential
h+

Front 21

___ - A redox reaction can be separated into its oxidation and reduction parts and a potential assigned to each half reaction
Half reactions are usually listed as ____.
To get ____ need to reverse the sign.

Back 21

Electrochemical Potential
reduction potentials
oxidation

Front 22

____ are usually represented by a capital E (in cursive)

Back 22

Reaction potentials

Front 23

____ are typically given as standard ____ at 25 degrees C. That means that the conditions are ____ - 1 molar for stuff in solution and 1 atm for gas.

Back 23

Reduction potential
Reduction potentials
standard state

Front 24

Gibbs free energy eq:
____

Back 24

ΔG = -nfe
ΔG is the change in gibbs free energy
N is the number of electrons when the equation is balanced.
F is faradays constant
E is the emf of the cell

Front 25

Superscript 0 signifies ____

Back 25

standard conditions

Front 26

____ - how to find the potential of a cell not at standard state conditions

Back 26

Nernst equation

Front 27

One common use is to find a cell potential of a concentration cell,

Back 27

Nernst equation

Front 28

____ - is a galvanic cell where the two half cells have the same reaction running in opposite directions.

Back 28

Concentration cell

Front 29

A galvanic cell cannot have ____.

Back 29

negative potential

Front 30

____, The cell will only run if the concentrations are different (hence the name) nature will try to equalize the concentrations of the two solutions
The ____ will be in the solution with less ions

Back 30

Concentration cell
anode

Front 31

ΔG0 = -RT ln k
If ΔG0 is positve ___
If ΔG0 is negative ____
If ΔG0 is zero ____

Back 31

then k is greater than 1
then k is less than 1
then k is equal to 1

Front 32

Battery at ____ = dead cannot do work

Back 32

equilibrium

Front 33

ΔG =

Back 33

ΔG0 + RT ln Q
R is the universal gas constant
T is the temperature
Q is the reaction quotient (from chem lecture 2)
Gibbs free energy amount of energy available to do non pv work.

Front 34

The ____ -
Battery you buy to power you stuff

Back 34

galvanic cell or voltaic cell

Front 35

The sum of the two half reactions is the ____ this is not a force it is a voltage.

Back 35

electromotive force or emf

Front 36

The emf is also called the ____, in a galvanic cell this must be ____.

Back 36

cell potential
positive

Front 37

Red Cat - and this is ____
An Ox - and this is ____

Back 37

positive
negative

Front 38

Galvanic/Voltaic Cell
The two halves must also be connected by a ____, this allows ions to transfer between the halves so that no charge buildup occurs.
The half reactions take place at the ____ in the half cells.

Back 38

salt bridge
electrodes

Front 39

____ - It separates the half reactions in separate reactions called half cells.
If the sum of the potentials of the two half cells is ____ the cell generates a ____ through the resistor transferring electrons from the solution in one ____ of the cell to the ____.

Back 39

Galvanic/Voltaic Cell
positive
current
half
other