Question

The molar mass of the water insoluble product formed from the fusion of chromite ore \(FeCr_2\text{O}_4\) with \(Na_2\text{CO}_3\) in presence of \(O_2\) is ....... g mol\(^{-1}\):

Answer 1

Correct Answer: 160

To resolve this issue, we must first ascertain the precipitate generated during the reaction and subsequently determine its molar mass.

1. Reaction Identification:
Chromite ore ($FeCr_2O_4$) undergoes reaction with sodium carbonate ($Na_2CO_3$) and oxygen ($O_2$) to yield sodium chromate ($Na_2CrO_4$), iron(III) oxide ($Fe_2O_3$), and carbon dioxide ($CO_2$).
The balanced chemical equation is:$4FeCr_2O_4(s) + 8Na_2CO_3(s) + O_2(g) \rightarrow 8Na_2CrO_4(aq) + 2Fe_2O_3(s) + 8CO_2(g)$

2. Insoluble Product Identification:
Within the reaction products, sodium chromate is soluble, whereas iron(III) oxide ($Fe_2O_3$) is insoluble.

3. Molar Mass Calculation for $Fe_2O_3$:
Provided data:Molar mass of Fe = 56 g/mol
Molar mass of O = 16 g/mol
Molar mass of $Fe_2O_3$ = (2 × Molar mass of Fe) + (3 × Molar mass of O) = (2 × 56 g/mol) + (3 × 16 g/mol) = 112 g/mol + 48 g/mol = 160 g/mol

Final Determination:
The molar mass of the insoluble product, $Fe_2O_3$, is 160 g/mol.