Question

For the reaction : $H_{2\left(g\right)}+C{l}_{2\left(g\right)}\to 2HCl;\Delta H=-44kcal$. What is the enthalpy of decomposition of $HCl$?

• A. + 44 kcal/mol
• B. - 44 kcal/mol
• C. - 22 kcal/mol
• D. +22 kcal/mol

Answer 1

The correct option is D +22 kcal/mol

$H_2\left(g\right)+{Cl}_2\left(g\right)⟶2HCl;\Delta H=-44kcal$

$\therefore 2HCl⟶H_2\left(g\right)+{Cl}_2\left(g\right);\Delta H=44kcal$

Therefore, enthalpy of decomposition of 2 moles of $HCl=44$ kcal

Therefore, enthalpy of decomposition of $HCl=$ $\frac{44}{2}kcal/mole=+22kcal/mol$