Question

The enthalpy of formation of hydrogen chloride (HCl) is \( -92.3 \, \text{kJ/mol} \). If 2 moles of HCl are formed from hydrogen and chlorine gas, calculate the total heat released.

• A. \( -184.6 \, \text{kJ} \)
• B. \( -92.3 \, \text{kJ} \)
• C. \( 92.3 \, \text{kJ} \)
• D. \( 184.6 \, \text{kJ} \)

Hint:

The enthalpy of formation is always given for the formation of 1 mole of a substance. When more than 1 mole is formed, multiply the enthalpy of formation by the number of moles.

Answer 1

The Correct Option is A

The enthalpy of formation (\( \Delta H_f^\circ \)) is the heat released or absorbed when 1 mole of a substance is formed from its elements in their standard states. For hydrogen chloride (HCl), the enthalpy of formation is given as \( -92.3 \, \text{kJ/mol} \). If 2 moles of HCl are formed, the total heat released is: \[ \text{Total heat} = 2 \times (-92.3) = -184.6 \, \text{kJ} \] Thus, the total heat released is \( -184.6 \, \text{kJ} \).