chem 108 exam 3

_________- occurs without outside intervention; goes in the indicated direction. (not related to rate, but may be T dependent)

________________- Law of conservation of energy. (Euniv is constant)

H = _______ (related to heat)

change in H = H_{____}- H_{_____} (is a state function)

change in H < 0 = ______ (usually spont)

change in H > 0 = ______

____________ - change to system is made in such a way that system can be restored to original state by exactly reversing the change.

______________- system must take another path to return original state.

___ = entropy (measure of disorder)

change is S= S_{____}-S_{_____}

______________ - in any spontaneous process there is an increase in the entropy of the universe.
S_univ = S_system + S_surroundings

__________________ - the entropy of a perfect crystal at 0 K is 0.

T affects magnitude of change in S effect

___= Gibbs Free Energy (also a state function)

change is G = change in H- TchangeinS and Change in G= change in G_final - G_{initial
**if change in G < 0, the process is spontaneous}

Change in G = -RT ln K

___________- study of relationships between electricity and chemical reactions

Oxidation-reduction (redox) reactions:

____-loss of electrons
_____- gain of electrons

Method of half-reactions:
1. Identify species being oxidized and reduced and write as half-reactions in the direction given
2. Balance each half-reaction by first balancing the element undergoing oxidation or reaction, then balance oxygens by adding H₂O, then balance hydrogens by adding H⁺ , then balance charge by adding e^-.
3. Multiply each balanced half-reaction by a common denominator to balance e^- loss and gain 
4. Add half-reactions back together to obtain balanced equation. Check for smallest coefficients.
5. If reaction is not in acidic solution, add OH^- to each side to neutralize all H⁺

__________- uses energy from spontaneous redox reaction to generate electricity by transfer of electrons through external pathway

____- electrode where oxidation occurs

_______- electrode where reduction occurs

_________- allows for passage of ions to maintain electrical neutrality

_______- driving force for electron flow; measured in volts; also called emf or electromotive force

__________________- potential of a half-reaction, written as a reduction, under standard conditions (P = 1 atm, [X] = 1 M), compared to the standard hydrogen electrode.

E°cell = E°cathode- E°anode

If Ecell > 0, this is a
________ process and the cell is a voltaic (galvanic) cell.

⋅change in G° = -nFE°
·n = moles e- changed
·F = Faraday's cst = 96,485 C/mole e-
·1 C = 1 amp x 1 sec
note= change in G= -RT ln K, so this is one
method of determining K

If Ecell < 0, this is a
________ process and the cell is an electrolytic cell. Dependence of cell
potential on concentration is given by the ____ equation:

E = E° - RT/nF ln Q

at 25° C, this may be simplified to 

E= E° - 0.0592V/n log Q

so one can calculate Ecell if concentrations are known.

At equilibrium, Q = __ and Ecell = _____ V, so this
becomes:

E° = 0.0592V/n log K, or 
log K= nE°/0.0592

medical applications of radioactivity:
1. tracers
2. cancer treatment

_______= voltaic cell or series of voltaic cells.

ex. Pb storage battery

*___________- voltaic cell with constant potential bc reactants are constantly added

______- naturally occuring oxidation of metals

*___________- forcing a current through a cell to drive a nonspontaneous reaction to occur

*___________ _________- time x current

1 F = 96,500 C/mole e-
     = 96,500 amp x sec

*______- subatomic particles

*_________= protons in nucleus (defines identity of element)

*________- sum of protons and neutrons for a particular nuclide

______- atom with a particular number of neutrons in nucleus

_________- decay of an unstable nucleus by emission of particles and/or electromagnetic radiation. A nucleus which is radioactive is
called a radionuclide or radioisotope

nuclear equations:

_______- (α) - ₂ ⁴He nucleus

₉₂²³⁸U → ₂⁴He + ₉₀²³⁴Th

*________-(β) - electron (e-) 


₉₀²³⁴Th→ - ⁰e + ₉₁²³⁴Pa

*_________- (β+) - positive electron (e+)

₁₁²²Na → +⁰e
+ ₁₀²²Ne

*___________- (γ) - high energy electromagnetic radiation (shorter ray than X-rays)

*_______- core electron captured by nucleus 

₈₀²⁰¹Hg + -⁰e → ₇₉²⁰¹Au+ γ

*__________- neutron/proton ratio; all nuclei with Z>84 are radioactive

*__________- conversion of one element into another (decay series)

*__________- transuranium elements (Z>92)

_______- radioactivity is 1st order
ln N/N0 = -kt

*_________- t½ = ln 2/k = 0.693 / k

isotopic dating - 614C (t½=
5730 yr)

detection techniques:
1. photographic film
2. Geiger counter
3. scintillation counter

*_______- E = mc2

*_________- difference in mass between a nucleus and the sum of its nucleons

*________- energy required to decompose a nucleus into its nucleons

______- splitting of heavy 
₉₂²³⁵U + ₀¹n → ₅₆¹⁴¹Ba+ ₃₆⁹²Kr + 3₀¹n

________- reactor types

*______- combining of lighter nuclei into heavier nuclei

₁¹H + ₁²H → ₂³He


_{note: radioactivity produces ionizing radiation which is harmful to living
organisms. However, since radioactive isotopes exist for all elements and many
occur naturally, we are constantly exposed to low levels of radioactivity.}

effects of radiation- depends upon:

1. E of radiation
2. penetrating ability
3. ionizing ability
4. chemical properties of element (biological concentration)

*_______- during lifetime of organism (burns, cancer, etc.)

*_________- evidenced in later generations (DNA alteration)