Question

Which equation do not represent enthalpy change of reaction which correspond to the standard enthalpy change of atomisation of chlorine?

• A. $\frac{1}{2}C{l}_2\left(g\right)\to Cl\left(g\right)$
• B. $\frac{1}{2}C{l}_2\left(l\right)\to Cl\left(g\right)$
• C. $C{l}_2\left(g\right)\to 2Cl\left(g\right)$
• D. $C{l}_2\left(l\right)\to 2Cl\left(g\right)$

Answer 1

Answer: (A), (B), (D)

$C{l}_2\left(l\right)\to 2Cl\left(g\right)$

Enthalpy of atomisation ${\Delta }_a{H}^o$ is the change in enthalpy when one mole of bond is completely broken to obtain atom in the gas phase.
$C{l}_2\left(g\right)\to 2Cl\left(g\right)$
Enthalpy change of the above reaction corresponds to standard enthalpy change of atomisation of chlorine as here one mole of chlorine gas is converted to 2 mole of chlorine atoms.