Question

Enthalpy of a solution of $CsBr\left(s\right)$ is $10kJ/mol$. If the enthalpies of hydration of $C{s}^{+}\left(g\right)$ and $Br\left(g\right)$ are 475 and 655 kJ.mol, what should be the lattice energy of $CsBr\left(s\right)$ in $kJ/mol$:

• A. $1120$
• B. $1130$
• C. $1140$
• D. $1150$

Answer 1

Answer: (A)

$1120$

$\Delta H_{solution}=\Delta H_{lattice}+\Delta H_{hydration}$

$\Delta H_{hydration}=475+655$

$10=\Delta H_{Lattice}+(475+655)$

$\Delta H_{Lattice}=1120$

Hence, option A is correct