# Chapter 9:Chemical Bonding I Basic Concepts¶

## Example no:9.13,Page no:397¶

In [4]:
#Variable declaration
#Type of bond broken:
hh_no=1         #No.of bonds broken
hh_be=436.4     #Bond enthalpy in kJ/mol
hh_ec=436.4     #Energy Change in kJ/mol
cl_no=1         #No.of bonds broken
cl_be=242.7     #Bond enthalpy in kJ/mol
cl_ec=242.7     #Energy Change in kJ/mol
#Type of bonds formed
hcl_no=2         #No.of bonds formed
hcl_be=431.9     #Bond enthalpy in kJ/mol
hcl_ec=863.8     #Energy Change in kJ/mol
#data:
Hf_hcl=-92.3     #Heat of formation of Hcl in kJ/mol
Hf_H2=0          #Heat of formation of H2 in kJ/mol
Hf_Cl2=0         #Heat of formation of Cl2 in kJ/mol

#Calculation
energy_in=hh_ec+cl_ec       #Total energy input in kJ/mol
energy_rlsd=hcl_ec          #Total energy released
delta_H=energy_in-energy_rlsd      #enthalpy change in kJ/mol
delta_Ho=2*(-92.3)-(Hf_H2+Hf_Cl2)    #Ethalpy change from eq 6.18

#Result
print "Using equation 9.3,delta_H=",delta_H,"kJ/mol"
print"Alternatively:"
print"Enthalpy change is:",delta_Ho,"kJ/mol"

Using equation 9.3,delta_H= -184.7 kJ/mol
Alternatively:
Enthalpy change is: -184.6 kJ/mol


## Example no:9.14,Page no:398¶

In [5]:
#Variable declaration
#Type of bond broken:
hh_no=2          #No.of bonds broken
hh_be=436.4      #Bond enthalpy in kJ/mol
hh_Ec=872.8      #Energy Change in kJ/mol
oo_no=1           #No.of bonds broken
oo_be=498.7       #Bond enthalpy in kJ/mol
oo_Ec=498.7       #Energy Change in kJ/mol
#Types of bond formed
nn_oh=4          #No.of bonds formed
nn_be=460        #Bond enthalpy in kJ/mol
bb_Ec=1840       #Energy Change in kJ/mol
#data:
Hf_h2o=-241.8     #Heat of formation of H2O in kJ/mol
Hf_h2=0           #Heat of formation of H2 in kJ/mol
Hf_O2=0           #Heat of formation of O2 in kJ/mol

#Calculation
energy_in=hh_Ec+oo_Ec       #Total energy input in kJ/mol
energy_rlsd=bb_Ec           #Total energy released
delta_h=energy_in-energy_rlsd            #enthalpy change in kJ/mol
delta_Ho=2*(Hf_h2o)-(2*Hf_h2+Hf_O2)      #Ethalpy change from eq 6.18

#Result
print"Enthalpy change is",delta_Ho,"kJ/mol"

Enthalpy change is -483.6 kJ/mol