Chemistry - Solid State Question with Solution | TestHub

Step 1: In an NaCl-type structure, the ideal number of formula units per unit cell is 4, giving 4 Cd²⁺ ions and 4 O²⁻ ions.

Step 2: For the non-stoichiometric compound CdO₀.₉₅, the number of Cd atoms remains 4, while the number of O atoms becomes $4\times 0.95=3.8$.

Step 3: The total mass of one unit cell is calculated as:

$$Mass=\frac{4\times 112+3.8\times 16}{6\times 10^{23}}=\frac{508.8}{6\times 10^{23}}g$$

Step 4: Using a standard edge length ($a=400pm=4\times 10^{-8}cm$), the density is:

$$\rho =\frac{Mass}{Volume}=\frac{508.8}{6\times 10^{23}\times (4\times 10^{-8}{)}^3}=13.25g/c{\mathbf{m}}^3$$