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A samlpe of 0.5 of an organic compound w...

A samlpe of 0.5 of an organic compound was analysed using Kjeldahl' method. The ammonia evolved was absorbed in 50 ml of 0.5 M `H_(2)SO_(4)`. The unsused acid after neutralisation by ammonia consumed 80 ml of 0.5N NaOH. Then calculate percentage of nitrogen in organic compound

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The correct Answer is:
28
Volume of acid taken ` = 50 mL of 0.5 M H_2SO_2`
Let the volume of the acid left unused ` = vmL` of `M//10H_2SO_4`
Applying molarity equation,
`n_a M_a V_(a)("acid") = n_bM_bV_b` (base), we have,
`2 xx 0.5 xx v = 1 xx 0.5 xx 80 or v = 40 mL ,
`:.` Volume of the acid used = 50 - 40
` = 10 mL` of 0.5 M `H_2SO_4`
Now %N `= (1.4 xx n_a M_aV_a)/("Wt. of substance taken")`
` = (1.4 xx 2 xx0.5 xx 10)/(0.5) = 28`.
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