The fusion of chromite ore with sodium carbonate in the presence of air leads to the formation of products A and B along with the evolution of ${CO}_{2}$ . The sum of spin-only magnetic moment values of A and B is ______ B.M. (Nearest integer)

(Given atomic number: C : 6, Na : 11, O : 8, Fe : 26, Cr : 24) [2024]

Question

The fusion of chromite ore with sodium carbonate in the presence of air leads to the formation of products A and B along with the evolution of ${CO}_{2}$ . The sum of spin-only magnetic moment values of A and B is ______ B.M. (Nearest integer)

(Given atomic number: C : 6, Na : 11, O : 8, Fe : 26, Cr : 24) [2024]

Smart Achievers · Accepted Answer

(6)

Dichromates are generally prepared from chromate, which in turn are obtained by the fusion of chromite ore $({FeCr}_{2} O_{4})$ with sodium or potassium carbonate in free access of air.

The fusion of chromite ore with sodium carbonate in the presence of air leads to the formation of sodium chromate $({Na}_{2} {CrO}_{4})$ and ferric oxide $({Fe}_{2} O_{3})$ .

$4 {FeCr}_{2} O_{4} + 8 {Na}_{2} {CO}_{3} + 7 O_{2} \to 8 {Na}_{2} {CrO}_{4} (A) + 2 {Fe}_{2} O_{3} (B) + 8 {CO}_{2}$

Compound	Electronic configuration of central atom	Spin only magnetic moment ( $μ = \sqrt{n (n + 2)} BM$ )
${Na}_{2} {CrO}_{4} (A)$	${Cr}^{6 +} = {}_{18}{[Ar]} 3 d^{0} 4 s^{0}$	$\sqrt{0 (0 + 2)} BM = 0 BM$
${Fe}_{2} O_{3} (B)$	${Fe}^{3 +} = {}_{18}{[Ar]} 3 d^{5} 4 s^{0}$	$\sqrt{5 (5 + 2)} BM = 5.92 BM$

Sum = 0 + 5.92 $≃$ 6.

Solution

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