Question

Find the simplest formula of a solid containing `A` and `B` atoms ia cubic arrangement In which `A` occuples corner and `B` the centre of the faces of unit cell. If the side length is `5 Å`, estimate the density of the solid assuming atomic weights of `A` and `B` as `60` and `90`, respectively.
A. `2g//cm^(3)`
B. `4g//cm^(3)`
C. `6g//cm^(3)`
D. `8g//cm^(3)`

Answer 1

Simple formula `AB_(3),Mw=60+3xx90=330`
Volume of unit cell=
`(5xx10^(-8))^(3)=125xx10^(-24)mL`
One cell has one `AB_(3)`, molecule So volume of one mole
`=125xx10^(-24)xx6.023xx10^(23)=75.287mL`
Density `=(330)/(75.287)=4.38gcm^(-3)`