Question

an impure sample of pyrolusite ore consist of 70 of mno2 20 inert impurities and rest moisture. On strong heating , all MnO2 is converted into MnO alongwith formation of O2 . The % of Mn in dried sample is (atomic mass of Mn = 55)

Answer 1

An impure sample of pyrolusite ore consist of:

70% of mno2

20% inert impurities

10% moisture

When dried it will contain = 70/90 * 100 = 77.78% MnO2


Mass of Mn in one mole of MnO2 = 55g

Molar mass of MnO2 = 55 + 2x16 = 87

Percentage of Mn in MnO2 = 55/87 * 100 = 63.22%


Percentage of Mn in dried sample of pyrolusite = 63.22% x 77.78

                                                                            = 49.17%

Answer 2

Explanation:

Ag3A = 3Ag + A

3 moles of Ag combine with 3 moles of A

Mass of Ag = 0.37

Mass of A = 607 - 0.37 = 606.63

Moles of Ag = 0.37/108 = 0.003426

Moles of A = 0.003426/3 = 0.001142

Molar mass of A = 606.63/0.001142 = 531211

A tribasic acid has 3 atom of H

Molar mass of the acid = 3 + 531211 = 531214 g/mol