Question

Calculate the % of MnO2 in a sample of pyrolusite ore, 1.5 g which was made to

react with 10 g of Mohr’s salt (FeSO4.(NH4)2SO4. 6H2O) and dilute H2SO4. MnO2 was

converted 2 Mn2+ . After the reaction the solution was diluted to 250 ml and 50 ml of

this solution, when titrated with 0.1 N K2Cr2O7, required 10 ml of the dichromate

solutio​

Answer 1

Answer:

Explanation:

milli equivalent when 50 ml solution = 1

milli equivalent when 250 ml solution = 5

milli equivalent of mohr salt = 0.0255*1000=25.5

difference in milli equivalent gives milli equivalent of mno2

milli equivalent of mno2=20.5

moles*2000=20.5

moles=0.01025

w/86.93=0.01025

w=1.09 gm

purity percentage = 1.09/1.5*100

=72.67