Question

For the reactions,

(i) $H_2\left(g\right)+{Cl}_2\left(g\right)=2HCl\left(g\right)+x$ $kJ$

(ii) $H_2\left(g\right)+{Cl}_2\left(g\right)=2HCl\left(l\right)+y$ $kJ$

which one of the following statements is correct?

• A. $x>y$
• B. $x<y$
• C. $x-y=0$
• D. $x=y$

Answer 1

The correct option is B $x<y$

(i) $H_2\left(g\right)+{Cl}_2\left(g\right)=2HCl\left(g\right)+x$ $kJ$

(ii) $H_2\left(g\right)+{Cl}_2\left(g\right)=2HCl\left(l\right)+y$ $kJ$

In 2${}^{nd}$ reaction the product $HCl$ formed is in liquid state while in 1${}^{st}$ reaction it is in gaseous state, so their will be some energy used in convert $HCl$ liquid into $HCl$ gas due to which the heat evolved in the reaction is less.

Hence, $x<y$. the answer is option $B$.