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Pyrolusite, `MnO_(2)`, is the main ore from which manganese is produced. The manganese content of the ore may be determined by reducing the `MnO_(2)` under acetic conditions to `Mn^(2+)` with the oxalate ion, `C_(2)O_(4)^(2-)`, the oxalate ion being oxidised to carbon dioxide during the reaction. The analytical determination is carried out by adding a known excess volume of oxalate solution to a suspension of the pyrolusite and digesting the mixture on a hot water bath until all the `MnO_(2)` has been reduced. The excess, unreacted oxalate solution is then titrated with standardised potassium permanganate, `KMnO_(4)` solution after which the manganese content of the ore can be calculated. A student prepared a standard solution of sodium oxalate by weighing 3.2 g of the dry anhydrous salt, dissolving it in distilled water and making the solution up to 500 mL. 25 mL of the oxalate solution required 24.76 mL of `KMnO_(4)` solution. What is the molarity of `KMnO_(4)` solution ?A. 0.04776B. 0.01929C. 0.038D. 0.028 |
| Answer» Correct Answer - B | |