Question

Select the incorrect stattement(s):

• A. Lattice energy $\propto \frac{1}{r^2}$. {where r is the interionic distance}
• B. Lattice energy $\propto q_1{q}_2$. {where $q_1$ and $q_2$ are the charges of co-ions}
• C. Ionic mobility of the ions in aqueous state $\propto \frac{1}{radiusofionsingaseousstate}$
• D. Heat of formation of a compound depends on the number of steps involved in its formation reaction

Answer 1

Answer: (A), (C), (D)

The correct options are
A Lattice energy $\propto \frac{1}{r^2}$. {where r is the interionic distance}
C Ionic mobility of the ions in aqueous state $\propto \frac{1}{radiusofionsingaseousstate}$
D Heat of formation of a compound depends on the number of steps involved in its formation reaction

(a) Lattice energy $\propto \frac{1}{r}$. hence (a) is wrong
(b) Correct
(c) Ionic mobility in aqueous state
$\propto \frac{1}{radiusofioninaqueousstate\left(HydrationRadii\right)}$
Hence (c) is wrong
(d) Violating Hess law. Hess's law states that energy changes are state functions and that the amount of energy depends only on the states of the reactants and the state of the products, but not on the intermediate steps. Enthalpy changes in chemical reactions are constant, irrespective of whether the reactions occur in a single or multiple steps.