Answer:
The answer is 8.0 x 10⁻⁸ pN
Explanation:
The equation of Coulomb's law is:
[tex]F=k_{e} \frac{q_{1}.q_{2} }{d^{2}}[/tex]
whereas:
- ke, Coulomb's constant, approx. 9 x 10⁹ N.m².C⁻²
- q₁, q₂: the quantity of charge of object 1 and object 2
- d: distance between two object, measured in meter
In our case,
- The absolute value of the charge of both K⁺ and Br⁻ is equal to the charge of an electron or proton, which is approx. 1.60 x 10⁻¹⁹ C
- d: distance between two object is the sum of both ion radius, which is 0.133 nm + 0.188 nm = 0.321 nm = 0.321 x 10⁻⁹ m
So the result is
9 x 10⁹ x 1.60 x 10⁻¹⁹ x 1.60 x 10⁻¹⁹ / 0.321 x 10⁻⁹ = 8.0 x 10⁻²⁰ N = 8.0 x 10⁻⁸ pN
