Question

Calculate the molar mass of an element having a density of 19.2 g cm⁻³ if it forms an fcc structure [a³ × N_A = 40 cm³ mol⁻¹].

Options

• 192 g mol⁻¹

• 186 g mol⁻¹

• 210 g mol⁻¹

• 280 g mol⁻¹

Answer 1

192 g mol⁻¹

Explanation:

ρ = `(M xx n)/(N_A (a)^3)`

M = `(ρ xx N_A xx (a)^3)/n`

= `(40  cm^3  mol^(-1))/4 xx 19.2  g  cm^-3`

= 192 g mol⁻¹