Potassium crystallizes in a body centred cubic lattice. Calculate the number of unit cells in 1g of potassium. Atomic mass of potassium = `39mu`.

Explanation

Molar mass of potassium, `M=39"g mol"^(-1)`
Mass of 1 atom of potassium `=M/(N_(A))`
`=(39"g mol"^(-1))/(6.022xx10^(23)"mol"^(-1))`
`=6.476xx10^(-23)g`
For b.c.c. strucutre, Z = 2
`therefore` Mass of 1 Unit Cell = `2xx6.476xx10^(-23)g`
`=12.95xx10^(-23)g=(100xx10^(21))/(12.95)`
`=7.7xx10^(21)`