Question

The attractive force between a pair of \(Li^+\) and \(Cl^-\) ions that touch each other is:

• A. \(F = 3.96 \times 10^{-9} \, \text{N}\)
• B. \(F = 4.96 \times 10^{-9} \, \text{N}\)
• C. \(F = 5.96 \times 10^{-9} \, \text{N}\)
• D. \(F = 6.96 \times 10^{-9} \, \text{N}\)

Hint:

In Coulombic interactions, ensure all values (e.g., distances) are in SI units for consistency. Ionic interactions like Li+ and Cl− are calculated using their effective radii.

Answer 1

The Correct Option is A

The force between two ions is determined by Coulomb's law:
\(F = \frac{q_1 q_2}{4\pi \epsilon_0 r^2}\)
Given $q_1 = q_2 = 1.6 \times 10^{-19}$ C, $r = 2.8 \times 10^{-10}$ m (representing the sum of ionic radii), and $\epsilon_0 = 8.854 \times 10^{-12}$ F/m, the calculated force is:
\(F = \frac{(1.6 \times 10^{-19})^2}{4\pi(8.854 \times 10^{-12})(2.8 \times 10^{-10})^2} \approx 3.96 \times 10^{-9} N\)