Perspective: a unit cell and a projection plan diagram
=0.1
Ca
00
OF
result in colored materials.
I. Yttrium(III) cations can be incorporated into the fluorite structure. For every Y that substitutes for a Ca, an extra F must be incorporated to maintain charge balance. If 1% of the Ca2 is substituted with Y, the formula for the compound is (ACaY.F BCaYF CCa0.01YF2.01 DCa0.99YF4.
4. The lattice energy of CaF can be calculated with a Born Haber cycle. Based on this calculation, what is the lattice energy of CaF? Ca(s) → Ca(g) + e- H=590 kJ/mol Ca(g) → Ca+(g) + e- H=1150 kJ/mol F2(g) → 2F(g) H=157 kJ/mol F(g) + C → F- H=-328 kJ/mol Ca(s) + C → CaF(s) H=178 kJ/mol Ca(s) + F2(g) → CaF2(s) H=-1220 kJ/mol ΔH = H-2H-H+H-H = -3124 kJ/mol
2. Which lattice describes the Ca arrangement in fluorite? A) simple cubic B) body-centered cubic C) face-centered cubic D) hexagonal close packed
ΔH = H-H-H+H-H = -2967 kJ/mol
3. How many anions are there per unit cell? (A) 12 (B) 8 (C) 4 (D) 2
ΔH = H-2H-H+H-2H = -2796 kJ/mol ΔH = H-H-H+H-2H = -2639 kJ/mol