Question

chromium crystallises in bcc structure .if its edge lenght is 300 pm .find its density .atomic mass of chromium is 52 u A=6.022x10'23mol-1 ​

Answer 1

edge length , a = 300pm = 300 × 10^-10cm

atomic mass of chromium , M = 52g/mol

number of atoms per unit cell of bcc, Z = 2

now, applying formula, $\rho=\frac{ZM}{a^3N_A}$

where , $\rho$ denotes density of chromium crystal and $N_A$ denotes Avogadro's number.

so, $\rho$ = 2 × 52/{(300 × 10^-10)³ × 6.023 × 10²³}

= 104/(27 × 10^-24 × 6.022 × 10²³)

= 104/(2.7 × 6.022)

= 6.396 g/cm³