NH 4 Br has a face-centered cubic unit cell in which the Br - anions occupy corn
ID: 834530 • Letter: N
Question
NH4Br has a face-centered cubic unit cell in which the Br- anions occupy corners and face centers, while the cations fit into the hole between adjacent anions. What is the radius of NH4+ if the ionic radius of Br- is 195.0 pm and the density of NH4Br is 2.429 g/cm3? Hint: notice that the cation and anion touch each other and together make up the side of the cube.
NH4Br has a face-centered cubic unit cell in which the Br- anions occupy corners and face centers, while the cations fit into the hole between adjacent anions. What is the radius of NH4+ if the ionic radius of Br- is 195.0 pm and the density of NH4Br is 2.429 g/cm3? Hint: notice that the cation and anion touch each other and together make up the side of the cube.
Explanation / Answer
Simply consider 1 cm^3 material. its mass is then2.429g, and it contains: (2.429/98)mol = 0.0247 mol. Since one mole atom is 6.022e23 atoms, this 1 cm^3 material contains 0.15e22 atoms.
If the material is in face-centered cubic structure, since a face-centered cubic unit cell holds four atoms, this 1 cm^3 material must contain 0.15e22/4 = 0.037e22 unit cells, and thus the side length of the unit cell must be (1/0.037e22)^(1/3) =90.09?
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.