Consider that AgX crystallizes in rock salt structure. The density of AgX is 6477 kg/m³ and unit cell length… · ABC26PH0541
Subject: Physical Chemistry · Chapter: Solid State Chemistry · Topic: Solid State – General · Exam: GATE 2005-2021 · Marks: 2 · Difficulty: Medium
Consider that AgX crystallizes in rock salt structure. The density of AgX is $6477\,\mathrm{kg/m^{3}}$ and unit cell length is 577.5 pm. Atomic weight of Ag is $107.87\,\mathrm{g\,mol^{-1}}$. The atomic weight of X (in $\mathrm{g\,mol^{-1}}$, rounded off to two decimal places) is ____
Answer
SELF-PRACTICE — the source book printed no answer.
Nothing is invented here, so this question has no answer on record.
Explanation
Answer: ≈ 79.94 g mol⁻¹ (X = Br) — M(AgX) = ρa³N_A/4 = 6477 × (5.775 × 10⁻¹⁰)³ × 6.022 × 10²³/4 = 0.18781 kg mol⁻¹ = 187.81 g mol⁻¹. X = 187.81 − 107.87 = 79.94, which is AgBr; the book's 78.33 is an arithmetic slip.