X-ray diffraction shows that the unit cell edge length of NaCl is 500 pm. If the measured density of — Solid State Chemistry Question

💡 Solution & Explanation

Theoretical density $d_{theo} = \frac{4 \times 58.5}{6 \times 10^{23} \times (5 \times 10^{-8})^3} = \frac{234}{6 \times 125 \times 10^{-1}} = \frac{234}{75} = 3.12 \text{ g/ml}$. The percentage of missing ions is given by $\frac{d_{theo} - d_{obs}}{d_{theo}} \times 100\% = \frac{3.12 - 2.964}{3.12} \times 100\% = \frac{0.156}{3.12} \times 100\% = 5\%$. Therefore, correct answer is 5.