An element crystallises in a fcc lattice with cell edge of 250 pm. Calculate the density if 300 g of this element contain `2xx10^(24)` atoms.

Explanation

300 g of the element contain `2xx10^(24)` atom. So, molar mass of the element = `300/(2xx10^(24))xx6.922xx10^(23)`
`=90.33g`
To calculate density `(rho)`, we use the formula, `rho=(ZxxM)/(Nxxa^(3))`
Putting the values of Z, M, N and a into the equation, we have, `rho=(4xx90.33)/(6.022xx10^(23)xx(250xx10^(-10)cm)^(3))`
`=38.4g*cm^(-3)" "[because"for fcc lattice Z = 4"]`