Investigating Chemical Bond Length and Energy

Table One: Average Bond Lengths and Energies

Bond
Length
pm
Energy
kJ/mol
C-O 143 341
C-C 154 332
C-Cl 177 326
Cl-Cl 199 243
Br-Br 229 193
I-I 266 151
H-H 75 436
H-C 109 418
H-Br 142 366
H-I 161 298

  1. Use the data in table one to determine a mathematical relationship between chemical bond length and bond energy.
  2. Explain the coefficients from your equation. (The value and the meaning)
  3. Calorimetric measurements have determined the bond energy of a hydrogen-chlorine bond to be 432 kJ/mol. Predict the length of this bond.
  4. X-ray diffraction techniques give a bond length for a carbon-bromine molecular bond of 194 pm. Determine the energy stored in a carbon-bromine bond.
  5. Microwave spectroscopic measurements determine the bond length of a hydrogen-chlorine bond to be 127 pm. Calculate the percent error in your calculation. Comment on the accuracy of your method in determining the H-Cl bond length.
  6. According to your data, how far apart do two atoms have to be in order to have a '0' bond energy? (It may be helpful to convert this distance into a more common unit).

Extension

C to C
kJ/mol
O to O
kJ/mol
C toO
kJ/mol
C to N
kJ/mol
Single
Bond		 347 142 360 305
Double
Bond		 611 498 728 615
Triple
Bond		 837 891

Predict the bond energies for an oxygen-oxygen and carbon-oxygen triple bond. (be careful)








Monday, February 28, 2000, KJC