Question

The energy of the C-C bond is 347 kJ/mol, and that of the Cl-Cl bond is 243 kJ/mol. Which of the following values might you expect for the C-Cl bond energy? Explain.
A) 590 kJ/mol (sum of the values given)
B) 104 kJ/mol (difference of the values given)
C) 295 kJ/mol (average of the values given)
D) 339 kJ/mol (greater than the average of the values given)

Answer 1

Answer:

C) 295 kJ/mol (average of the values given)

Explanation:

We can use Hess' Law to calculate the energy of formation of the C-Cl bond:

C-C → 2C  ΔH = -347 kJ/mol

Cl-Cl → 2Cl  ΔH = -243 kJ/mol

_______________________

C + Cl → C-Cl       ΔH = (-347/2)+(-243/2)

ΔH = -295 kJ/mol

Answer 2

Answer:

D) 339 kJ/mol (greater than the average of the values given)

Explanation:

The bond energy is the measure of bond strength in a chemical bond.

Both C-C and Cl-Cl bond are non-polar chemical bonds that satisfy the octet rule, for that reason are strong bonds. Carbon can form 3 additional bonds giving an additional bond strength.

The C-Cl bond is a bond that satisfy octet rule but is a polar bond that gives an additional strength bond. For that reason it is possible to expect for the C-Cl bond energy:

D) 339 kJ/mol (greater than the average of the values given)

I hope it helps!