Caesium chloride (CsCI), used in DNA separation and nuclear medicine, forms salt
ID: 1524203 • Letter: C
Question
Caesium chloride (CsCI), used in DNA separation and nuclear medicine, forms salt crystals built from the unit cells shown in the figure below. Cl^- ions form the corners of a cube and a Cs^+ ion is at the centre of the cube. The edge length of the cube, which is called the lattice constant, is 0.4 nm. What is the magnitude of the net force (in N) exerted on the cesium ion by its eight nearest Cl^- neighbours? If the Cl^- in the lower left corner is removed, what is the magnitude of the net force (in N) exerted on the cesium ion at the centre by the seven remaining nearest chlorine ions? In what direction does this force act on the cesium ion? toward the corner with the removed Cl^- away from the corner with the removed Cl^-Explanation / Answer
a) magnitude of net force = 0 N
b) magnitude of net force = 8.98 * 109 * 1.6 * 10-19 * 1.6 * 10-19/(0.346 * 10-9)2
= 1.92 * 10-9 N
Direction = away from the corner with the removed Cl- .