Question

Why does Frenkel defect not change the density of AgCl crystals?

Answer 1

1. The Frenkel defect does not change the density of AgCl crystals because it involves only the displacement of ions within the crystal, not their removal or addition.
2. In a Frenkel defect, a smaller ion (usually a cation like Ag⁺) leaves its regular lattice site and moves to an interstitial position within the same crystal. This creates a vacancy at the original site and an interstitial defect, but the total number of ions and the total mass remain unchanged.
3. In AgCl, the smaller Ag⁺ ion can move into an interstitial site, while the larger Cl⁻ ion remains in place.
4. Since density = `"mass"/"volume"`, and neither the mass nor the volume of the crystal changes significantly, the density remains the same. Therefore, the Frenkel defect does not affect the density of AgCl crystals.