The density of potassium bromide crystal is `2.75 g cm^(-3)` and the length of an edge of a unit cell is 654 pm. The unit cell of KBr is one of three types of cubic unit cells. How many formula units of KBr are there in a unit cell ? Does the unit cell have a NaCl or CsCl structure ?

The density of potassium bromide crystal is `2.75 g cm^(-3)` and the l

1.	The density of potassium bromide crystal is `2.75 g cm^(-3)` and the length of an edge of a unit cell is 654 pm. The unit cell of KBr is one of three types of cubic unit cells. How many formula units of KBr are there in a unit cell ? Does the unit cell have a NaCl or CsCl structure ?
Answer» We know that, `rho=(N)/(a^(3))[(M)/(N_(A))]` `N=(rhoxxa^(3)xxN_(A))/(M)` `=(2.75xx(654xx10^(-10))^(3)xx6.023xx10^(23))/(119)=3.89 ~~4` Number of mass points per unit cell =4 It is NaCl type crystal, i.e., fcc structure.

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The density of potassium bromide crystal is `2.75 g cm^(-3)` and the length of an edge of a unit cell is 654 pm. The unit cell of KBr is one of three types of cubic unit cells. How many formula units of KBr are there in a unit cell ? Does the unit cell have a NaCl or CsCl structure ?

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