Question

Enthalpy of formation of HF and HCl are \(-161\) kJ and \(-92\) kJ, respectively. Select the incorrect statement on the basis of the above fact.

• A. HF is more stable than HCl
• B. HCl is more stable than HF
• C. Affinity of fluorine to hydrogen is greater than affinity of chlorine to hydrogen
• D. HF and HCl are exothermic compounds

Hint:

A more negative standard enthalpy of formation indicates a more stable compound.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
More negative enthalpy of formation indicates greater stability of the compound.

Step 2: Detailed Explanation:
The enthalpy of formation (\(\Delta_f H^\circ\)) for HF is -161 kJ/mol, and for HCl is -92 kJ/mol. • A more negative \(\Delta_f H^\circ\) means the compound is more stable (lower in energy). • Since -161 < -92, HF is more stable than HCl. • The greater stability of HF indicates a stronger H-F bond and a higher affinity of fluorine for hydrogen compared to chlorine. • Both values are negative, so both compounds are exothermic. Statement (B) is the opposite of the correct fact.

Step 3: Final Answer:
The incorrect statement is that HCl is more stable than HF, which corresponds to option (B).