Key Equations in Physical Chem

Question 1

write the equation for transmission probability

Answer 1

T= [1+ (e^kappaL-e^-kappaL)^2/16xepsilonx(1-epsilon) ]^-1

Question 2

what is epsilon?

Answer 2

epsilon=E/V

Question 3

what is kappa? write out eq

Answer 3

kappa= [2m(V-E)]^1/2 / hbar

Question 4

write out equation for kinetic energy involving work function
What value does Ke have at threshold

Answer 4

Ke=1/2 x me x v^2 =
hv-PHI
at threshold, Ke=0

Question 5

wite down the two secular equations involving heteroatoms

Answer 5

alpha(x)=
alpha(c)+h(x)Beta(cc)
Beta(cx)=
K(cx)Beta(cc)

Question 6

what is x equal to when considering secular equations?

Answer 6

x=(alpha-E)/Beta

Question 7

what is the wavefunction of a particle within finite barrier

Answer 7

wf=Ce^-kx

Question 8

write the secular determinant of a 2 membered carbon molecule

Answer 8

Alpha-E Beta |
| Beta Alpha-E|=0

Question 9

how do you find allowed energy levels within harmonic oscillator?

Answer 9

Ev=(v+1/2)hbarw
hbar = plancks/2Pi
w = (Kf/m)^1/2

Question 10

how do you find energy of excitation from Hydrogenic atoms?

Answer 10

En=-Z^2/2n^2 x Eh
Eh=Hartrees energy
Z=atomic no.
n=valence shell

Question 11

how do you find ionisation energy from energy of excitation?

Answer 11

IE=-En

Question 12

What are the basic steps to the Huckel theory?
write them down

Answer 12

write LCAO, write determinant, expand and solve for x,
use E=Alpha - xBeta to find coefficients.

Question 13

What is the equation linking chemical potential and standard chemical potential?
Units?

Answer 13

u=u(standard) +RTln(p/p(standard)
pressures in bar
u given in J mol^-1

Question 14

How do you fid the Gibbs E of mixture using compositions?
Units?

Answer 14

DeltaG=nrt(XaLn(Xa) +XbLn(Xb))
DeltaG given in J

Question 15

How do you find the extent of reaction at equilib?

Answer 15

at equilibrium Q=K
set up table showing start and end conc of products/reactants
set up equilibrium constant equation and solve for X

Question 16

What equation links together change in Entropy, Enthalpy and temp?

Answer 16

Change in molar entropy/change in ln(T) = heat capacity

Question 17

Whats the equation linking molar enthalpy, temperature and pressure

Answer 17

ln(P)=(DeltaHm/R x 1/T) +c

Question 18

How do you work out the distance between ions in a fcc/bcc lattice unit from a?

Answer 18

for fcc axroot3/4
d111 plane used hence root3
for bcc axroot2/4
d110 plane hence root2

Question 19

define the photoelectric effect

Answer 19

emission of an electron from a solid metal caused by electromagnetic radiation. frequency of radiation has to be above threshold for electron to be emitted