from __future__ import division
import math
#Python Ex2.1 Stability of molecule on bond dissociation energy:Page-61 (2010)
#Variable declaration
e = 1.6*10**-19; # Electronic charge, C
N = 6.023*10**+23; # Avogadro's number
#Absolute Electrical permitivitty of free space,
#coulomb square per newton per metre square
e0 = 8.854*10**-12;
Re = 3*10**-10; # Equilibrium separation, m
IE = 502; # First ionization energy of A, kJ/mol
EA = 335; # Electron affinity for atom B, kJ/mol
IS = 3*10**-10; # Interatomic separation between A+ and B-, m
#Calculation
# Potential energy at equilibrium separation of A+B- molecule, kJ/mol
Ue = -(e**2*N)/(4*math.pi*e0*Re*1*10**+3);
DE = Ue + IE - EA; # Bond dissociation energy of A+B- molecule, kJ/mol
#Result
print"\nThe bond dissociation energy of A+B- molecule is :",round(DE)," kJ/mol"
if(DE<0):
print "The molecule A+B- is stable.."
else:
print "The molecule A+B- is unstable.."
from __future__ import division
import math
# Python Code Ex2.2 Conversion of eV into kcal/mol: Page-64 (2010)
#Variable declaration
e = 1.6*10**-19; # Electronic charge, C
N = 6.023*10**+23; # Avogadro's number
J = 4.184*10**+3; # Joule's mechanical equivalent of heat
V = 1; # Potential difference, V
#Calculation
eV = e*V; # Energy equivalent of 1 electron-volt, J
eVpm = eV*N; # Electron-volt per mole, J/mol
Ecal = eVpm/J; # Energy equivalent of 1eV, kcal/mole
#Result
print"\n1 eV is approximately equal to :",round(Ecal,2),"kcal/mol"
from __future__ import division
import math
# Python Code Ex2.3 Potential energy of the system of
# Na+ and Cl- ions: Page-68 (2010)
#Variable declaration
e = 1.6*10**-19; # Electronic charge, C
ep_0 = 8.854*10**-12;#Absolute electrical permittivity of free space,
#coulomb square per newton per metre square
Re = 2*10**-10;#Equilibrium separation between Na+ and Cl- ions, m
#Calculations
#Potential energy of NaCl molecule at equilibrium separation, electron-volt
U = -e/(4*math.pi*ep_0*Re);
#Result
print"\nThe potential energy of NaCl molecule "
print "at equilibrium separation5 is :",round(U,1),"eV"
from __future__ import division
import math
#Python CodeEx2.4Compressibility and ionic energy of NaCl crystal:Page-68(2010)
#Variable declaration
e = 1.6*10**-19; # Electronic charge, C
ep_0 = 8.854*10**-12; # Absolute electrical permittivity of free space,
# coulomb square per newton per metre square
Re = 2.81*10**-10;#Equilibrium separation between Na+ and Cl- ions, m
A = 1.7496; # Madelung constant
n = 9;#Power of R in the repulsive term of potential energy of two particles
IP_Na = 5.14; # Ionization potential of sodium, eV
EA_Cl = 3.61; # Electron Affinity of chlorine, eV
#Calculation
# Compressibilty of NaCl crystal, metre square newton
K0 = (72*math.pi*ep_0*Re**4)/((n - 1)*A*e**2);
# Potential energy of NaCl molecule at equilibrium separation,electron-volt
U = -(A*e)/(4*math.pi*ep_0*Re)*(1-1/n);
U_bar = U/2; # Potential energy per ion, electron-volt
delta_E = IP_Na - EA_Cl;#Energy required to produce the ion-pair, eV
E_ion = delta_E/2; # Energy required to produce per ion, eV
C_E = U_bar + E_ion; # Cohesive energy per ion, eV
#Result
print"\nThe compressibility of NaCl crystal is"
print round(K0*10**(11),2)*10**-11,"metre square newton"
print"\nThe cohesive energy of NaCl crystal is",round(C_E,2),"eV"
from __future__ import division
import math
#Python CodeEx2.5 Potential energy and dissociation energy
# of a diatomic molecule: Page-69 (2010)
#Variable declaration
e = 1.6*10**-19; # Electronic charge, C
A = 1.44*10**-39;#Constant corrsponding to the attractive term
# in potential energy, joule metre square
B = 2.19*10**-115; # Constant corresponding to the repulsive term
#in potential energy, joule metre raised to power 10
#Calculation
Re = (5*B/A)**(1/8);#Equilibrium spacing of diatomic molecule, m
n = 2;#Power of R in the attractive term of potential energy of two particles
m = 10;#Power of R in the repulsive term of potential energy of two particles
D = A/(Re**2*e)*(1-n/m) #Dissociation energy of diatomic molecule, eV
#Result
print"\nThe equilibrium spacing of diatomic molecule is"
print round((Re*10**10),2)*10**-10,"m"
print"\nThe dissociation energy of diatomic molecule is",round(D,3),"eV"
from __future__ import division
import math
# Python Code Ex2.6 Binding force and critical separation of
#a diatomic molecule: Page-69 (2010)
#Variable declaration
Re = 3*10**-10; # Equilibrium spacing of diatomic molecule, m
e = 1.6*10**-19; # Electronic charge, C
n = 2;#Power of R in the attractive term of potential energy of two particles
m = 10;#Power of R in the repulsive term of potential energy of two particles
#Calculations
D = 4*e; # Dissociation energy of diatomic molecule, eV
Ue = -D;#Potential energy of diatomic molecule at equilibrium separation,joule
A = -(Ue*Re**n)/(1-n/m);#Constant corrsponding to the attractive term
# in potential energy, joule metre square
B = A*Re**8/5; # Constant corresponding to the repulsive term
# in potential energy, joule metre raised to power 10
Rc = (55/3*B/A)**(1/8); # Critical separation between the nuclei, m
F_min = -2*A/Rc**3*(1-(Re/Rc)**8);# The minimum force required to
# dissociate the moleule, N
#Results
print "The constant A corresponding to "
print "the attractive potential energy, in joule metre square, is :",A
print "The constant B corresponding to"
print"the repulsive potential energy,in joule metre raised to power 10,is:"
print round((B*10**115),2)*10**-115
print "The critical separation between the nuclei, in angstrom, is : "
round ((Rc*10**10),2)*10**-10
print "The minimum force required to dissociate the molecule,in N,is:"
print round((F_min*10**9),2)*10**-9
from __future__ import division
import math
#Python Code Ex2.7Bond formation Energy for K+ and Cl- ion pair:Page-70(2010)
#Variable declaration
eps_0 = 8.854*10**-12;# Absolute electrical permittivity of free space,
# coulomb sqaure per newton per metre square
e = 1.6*10**-19; # Electronic charge, C
IP_K = 4.1; # Ionization potential of potassium, electron-volt
EA_Cl = 3.6; # Electron affinity of chlorine, electron-volt
#Calculations
delta_E = IP_K - EA_Cl; # Net energy required
#to produce the ion-pair, electron-volt
Ec = delta_E; # Coulomb energy equals net energy required
# to produce the ion pair, in electron-volt
# Since Ec = -e/(4*%math.pi*eps_0*R), solving for R
R = -e/(4*math.pi*eps_0*Ec);#Separation between K+ and Cl- ion pair, m
#Results
print "The bond formation energy for K+ and Cl- ion pair, in eV, is : ",Ec
print"The separation between K+ and Cl- ion pair,in angstrom,is"
print round(R/(1*10**-10),2)
from __future__ import division
import math
# Python Code Ex2.8 Energy liberated during electron transfer
# between ions of a molecule: Page-71 (2010)
#Variable declaration
eps_0 = 8.854*10**-12; # Absolute electrical permittivity of free space, # Electronic charge, C
R = 5*10**-10; # Separation between the ions M and X, m
e=1.6*10**-19
IP_M = 5; # Ionization potential of M, eV
EA_X = 4; # Electron affinity of X, eV
#Calculations
U = -e/(4*math.pi*eps_0*R); # The potential energy of MX molecule, eV
delta_E = IP_M - EA_X;#The net energy required to produce the ion pair, eV
Er = delta_E + U;#Energy required to transfer an electron from M to X eV
#Result
print"\nEnergy to transfer an electron from M to X atom=",round(Er,2)," eV"