Lithium borohydride ( LiBH 4), crystallises in an orthorhombic system with 4 molecules per unit cell. The unit cell dimensions are: a =6.81 A , b =4.43 A , c =717 A. If the molar mass of LiBH 4 is 21.76 g mol -1. The density of the crystal is -

Question

Lithium borohydride ( LiBH 4), crystallises in an orthorhombic system with 4 molecules per unit cell. The unit cell dimensions are: a =6.81 A , b =4.43 A , c =717 A. If the molar mass of LiBH 4 is 21.76 g mol -1. The density of the crystal is - (A)  (B)  (C)  (D)

Tardigrade Admin · Accepted Answer

We know that, ρ=(Z M/N V) =(4 ×(21.76 g mol -1)/(6.023 × 1023 mol -1)(6.81 × 4.43 × 7.17 × 10-24 cm 3)) =0.668 g cm -3

Q. Lithium borohydride $(L i B H_{4})$ , crystallises in an orthorhombic system with $4$ molecules per unit cell. The unit cell dimensions are : $a = 6.81 A, b = 4.43 A, c = 717 A$ . If the molar mass of $L i B H_{4}$ is $21.76 g m o l^{- 1}$ . The density of the crystal is -

We know that,
$ρ = \frac{ZM}{N V}$
$= \frac{4 \times ( 21.76 g m o l ^{- 1} )}{( 6.023 \times 1 0 ^{23} m o l ^{- 1} ) ( 6.81 \times 4.43 \times 7.17 \times 1 0 ^{- 24} c m ^{3} )}$
$= 0.668 g c m^{- 3}$

Q. Lithium borohydride (LiBH4​), crystallises in an orthorhombic system with 4 molecules per unit cell. The unit cell dimensions are : a=6.81A,b=4.43A,c=717A. If the molar mass of LiBH4​ is 21.76gmol−1. The density of the crystal is -

We know that, ρ=NVZM​ =(6.023×1023mol−1)(6.81×4.43×7.17×10−24cm3)4×(21.76gmol−1)​ =0.668gcm−3

Q. Lithium borohydride $(L i B H_{4})$ , crystallises in an orthorhombic system with $4$ molecules per unit cell. The unit cell dimensions are : $a = 6.81 A, b = 4.43 A, c = 717 A$ . If the molar mass of $L i B H_{4}$ is $21.76 g m o l^{- 1}$ . The density of the crystal is -

We know that,
$ρ = \frac{ZM}{N V}$
$= \frac{4 \times ( 21.76 g m o l ^{- 1} )}{( 6.023 \times 1 0 ^{23} m o l ^{- 1} ) ( 6.81 \times 4.43 \times 7.17 \times 1 0 ^{- 24} c m ^{3} )}$
$= 0.668 g c m^{- 3}$