Question

Consider the table below, showing the formation of the hydrogen halides, with their accompanying $△H^{\circ }$ and $△S^{\circ }$ values. Assume each reaction occurs at constant pressure.

	Reaction	$△H^{\circ }$	$△S^{\circ }$
A	$H_2\left(g\right)+F_2\left(g\right)\to 2HF\left(g\right)$	$-273kJ/mol$	$+174J/molK$
B	$H_2\left(g\right)+C{l}_2\left(g\right)\to 2HCl\left(g\right)$	$-92kJ/mol$	$+187J/molK$
C	$H_2\left(g\right)+B{r}_2\left(l\right)\to 2HBr\left(g\right)$	$-36kJ/mol$	$+199J/molK$
D	$H_2\left(g\right)+I_2\left(s\right)\to 2HI\left(g\right)$	$+27kJ/mol$	$+207J/molK$

Which of the four statement is TRUE, based on the information in the table?

• A. Of the four hydrogen, only Reaction A is spontaneous at all temperatures.
• B. Reaction A will have the greatest rate of reaction.
• C. Hydrogen fluoride, $HF$, had the greatest bond dissociation energy of the four hydrogen halides.
• D. Of the four, only Reaction D is spontaneous at all temperatures.

Answer 1

The correct option is C Hydrogen fluoride, $HF$, had the greatest bond dissociation energy of the four hydrogen halides.

$\text{Since formation of HF released more energy so for dissociation also it need more enrgy. So option C is true.}$