Question

The lattice enthalpy and hydration enthalpy of four compounds are given below:

Compound	Lattice enthalpy $\left(kJ/mol\right)$	Hydration enthalpy $\left(kJ/mol\right)$
$P$	$+780$	$-920$
$Q$	$+1012$	$-812$
$R$	$+828$	$-878$
$S$	$+632$	$-600$

The pair of compounds which is soluble in water is:

• A. $P$ and $Q$
• B. $Q$ and $R$
• C. $R$ and $S$
• D. $Q$ and $S$
• E. $P$ and $R$

Answer 1

Answer: (E)

$P$ and $R$

for solubility in water

(lattice enthalpy $+$ hydration enthalpy ) should be negative . only true for $P$ and $R$.