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A SAMPLE OF MAGNESIUM WAS BURNT IN AIR TO GIVE A MIXTURE OF MgO AND Mg3N2. THE ASH WAS DISSOLVED IN 60 m.eq. OF HCI AND THE RESULTING SOLUTION WAS BACK TITRATED WITH NaOH, 12 m.eq. OF NaOH WERE REQUIRED TO REACH THE END POINT. AN EXCESS OF NaOH WAS THEN ADDED AND THE SOLUTION DISTILED. THE AMMONIA RELEASED WAS THEN TRAPPED IN 10 m.eq. OF SECOND ACID SOLUTION. BACK TITRATION OF THIS SOLUTION REQUIRED 6m.eq. OF THE BASE. CALCULATE THE PERCENTAGE OF MAGNESIUM BURNT TO THE NITRIDE.

shailesh_45

even i don't know how to solve it ,can someone ans this question

krishna.gopal

You added 60 meq of HCl and 12 meq of NaOH was required to titrate it. So 48 Meq of HCl reacted with Mg oxide and nitride. So there was 48 meq of Mg. As ammonia reacted with 10 meq acid. So there was 10 meq nitride and remaining 38 meq oxide.
So percent of Mg going to nitride = 10*100/48

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