import math
#Variable declaration
atoms=8*1.0/8.0+6*1.0/2.0 #atoms in a cell
d=19.3 #density, g/cc
Au=197.0 #mol mass of Au, g
NA=6.022*10**23 #avogadro no.
#Calculation
m=atoms*Au/NA #mass of 1 cell, g
V=m/d #volume, cc
a=V**(1/3.0) #edge length, cm
r=a/math.sqrt(8.0)/100.0 #radius in m
#Result
print"The atomic radius of Au is :",round(r*10**12),"pm"
import math
#Variable declaration
n=1.0
lamda=154 #wavelength, pm
theta=19.3 #angle of reflection, degree
#Calculation
d=n*lamda/(2*math.sin(theta*math.pi/180.0)) #spacing between the planes
#Result
print"The spacing between planes is :",round(d),"pm"
#Variable declaration
Na=22.99 #mass of one atom of Na, amu
Cl=35.45 #mass of one atom of Cl, amu
NA=6.022*10**23 #avogadro no.
#Calculation
mass=4*(Na+Cl)/NA #mass in a unit cell in grams
a=564*10**-10 #edge length, cm
V=a**3 #volume of unit cell, cc
d=mass/V #density in g/cc
#Result
print"The density of NaCl is :",round(d,2),"g/cm**3"
import math
#Variable declaration
P1=401.0 #vapor pressure at 18C, mm Hg
T1=18.0+273.0 #temperature, K
T2=32.0+273.0 #temperature, K
deltaH=26000.0 #heat of vaporisation, J/mol
R=8.314 #gas constant, J/K.mol
#Calculation
X=deltaH/R*(T1-T2)/(T1*T2)
P2=401*math.exp(-X) #vapor pressure at 32C, mmHg(from ln(P1/P1)=deltaH/R*((T1-T2)/(T1*T2)))
#Result
print"The pressure at 32 C is ",round(P2,1),"mm Hg"
#Variable declaration
m=346 #mass of H2O in g
s=4.184 #specific heat of H2O, J/g C
deltaH=40.79 #heat of vaporisation in kJ
H2O=18.02 #mol mass of H2O, g
s2=1.99 #specific heat of steam, J/g C
#Calculation
#from 0 to 100 C
deltaT=100.0-0.0 #change in Temp, C
q1=round((m*s*deltaT)/1000.0) #heating H2O, kJ
#for evaporation at 100 C
deltaT2=182-100 #change in temp of steam, kJ
q2=round(m*deltaH/H2O) #heat of vaporising water, kJ
#for steam from 100 to 182 C
q3=round(m*s2*deltaT2/1000.0,1) #heating steam, kJ
q=round(q1)+round(q2)+round(q3,1) #overall energy required, kJ
#Result
print"The overall energy required is :",round(q),"kJ"