NH4Br has a face-centered cubic unit cell in which the Br- anions occupy corners and face centers, while the cations fit into the hole between adjacent anions. What is the radius of Br- if the ionic radius of NH4 is 138.3 pm and the density of NH4Br is 2.429 g/cm3

Ionic radius of the bromide ion is 227.9 pm.

Explanation:

Number of atom in FCC unit cell = Z = 4

Density of ammonium bromide =

Edge length of cubic unit cell= a= ?

Molar mass of ammonium bromide = 98 g/mol

Formula used :  

where,

= density

Z = number of atom in unit cell

M = atomic mass

= Avogadro's number  

a = edge length of unit cell

On substituting all the given values , we will get the value of 'a'

Ionic radius of bromide ion = r

To calculate the edge length, we use the relation between the radius and edge length for FCC lattice:

Putting values in above equation, we get:

Ionic radius of the bromide ion is 227.9 pm.

in 1783 cavendish was working with his hydrogen gas and found that when he burned it and condensed the vapor it was water. this was very significant since it disproved the greek theory of elements completely since water was not a simple substance but the product of two gases. it was lavoisier who hearing of the experiment gave cavendish's gas the name hydrogen ("water-producer") and added that hydrogen burned by combining with oxygen and that water was a hydrogen-oxygen combination.

explanation: