Question

Bond enthalpies of \( H_2 \), \( X_2 \), and \( HX \) are in the ratio 2:1:2. If enthalpy of formation of \( HX \) is -50 kJ/mol\(^{-1}\), the bond enthalpy of \( X_2 \) is:

• A. 100 kJ/mol\(^{-1}\)
• B. 300 kJ/mol\(^{-1}\)
• C. 200 kJ/mol\(^{-1}\)
• D. 400 kJ/mol\(^{-1}\)

Hint:

Bond enthalpies can be used to calculate enthalpy changes based on the ratio of bond strengths in the molecules involved.

Answer 1

The Correct Option is A

Step 1: Bond enthalpy relationship.
Using the given bond enthalpies and enthalpy of formation, we can set up the following relation: \[ \text{Bond enthalpy of } X_2 = 100 \, \text{kJ/mol} \] This is calculated based on the given ratio and the bond enthalpy formula.
Thus, the correct answer is (1).