A 0.166 g sample of an organic compound was digested with conc. and then distilled with NaOH. The ammonia gas evolved was passed through 50.0 mL of . The used acid required 30.0 mL of 0.25 N NaOH for

Question

A 0.166 g sample of an organic compound was digested with conc.  and then distilled with NaOH. The ammonia gas evolved was passed through 50.0 mL of . The used acid required 30.0 mL of 0.25 N NaOH for complete neutralization. The mass percentage of nitrogen in the organic compound is

Canvas Classes · Accepted Answer

Step 1 — meq of  taken (to absorb NH₃):

meq

Step 2 — meq of NaOH used for back-titration:

meq

Step 3 — meq of  absorbed (= meq of acid neutralised by NH₃):

meq of acid neutralised by NH₃ = 25 − 7.5 = 17.5 meq

Wait — back-titration: excess acid (not neutralised by NH₃) = 7.5 meq (neutralised by NaOH).

So meq of NH₃ = 25 − 7.5 = 17.5 meq

Step 4 — mol of N:

mol (since NH₃ is monoprotic, meq = mmol)

Step 5 — mass of N:

g

Step 6 — % N:

This exceeds 100%, indicating the question dat

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