While estimating the nitrogen present in an organic compound by Kjeldahl’s method, the ammonia evolved from 0.25 g of the compound neutralized 2.5 mL of M H₂SO₄. The percentage of nitrogen present in organic compound is _________.

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Vishal Baghel | Contributor-Level 10

4 months ago

Organic compound -> NH₃

$2 N H_{3} + H_{2} S O_{4} \to {(N H_{4})}_{2} S O_{4}$

No. of millimoles of NH₃ = 2 × no. of milimoles of H₂SO₄

= 2 × 2 × 2.5

= 10 milimoles

= No. of milimoles of N

Mass of nitrogen = $\frac{10}{100} \times 14 = 0.14 g m$

% of Nitrogen in compound = $\frac{0.14}{0.25} \times 100$

= 56%

Organic compound -> NH3<!- [if gte mso 9]><xml> <o:OLEObject Type="Embed" ProgID="Equation.DSMT4" ShapeID="_x0000_i1025" DrawAspect="Content" ObjectID="_1814949283"> </o:OLEObject></xml><! [endif]-> <math> <mrow> <mn>2</mn> <mi>N</mi> <msub> <mrow> <mi>H</mi> </mrow> <mrow> <mn>3</mn> </mrow> </msub> <mo>+</mo> <msub> <mrow> <mi>H</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msub> <mi>S</mi> <msub> <mrow> <mi>O</mi> </mrow> <mrow> <mn>4</mn> </mrow> </msub> <mo>→</mo> <msub> <mrow> <mrow> <mo> (</mo> <mrow> <mi>N</mi> <msub> <mrow> <mi>H</mi> </mrow> <mrow> <mn>4</mn> </mrow> </msub> </mrow> <mo>)</mo> </mrow> </mrow> <mrow> <mn>2</mn> </mrow> </msub> <mi>S</mi> <msub> <mrow> <mi>O</mi> </mrow> <mrow> <mn>4</mn> </mrow> </msub> </mrow> </math>  No. of millimoles of NH3 = 2 × no. of milimoles of H2SO4= 2 × 2 × 2.5= 10 milimoles= No. of milimoles of NMass of nitrogen = <!- [if gte mso 9]><xml> <o:OLEObject Type="Embed" ProgID="Equation.DSMT4" ShapeID="_x0000_i1026" DrawAspect="Content" ObjectID="_1814949284"> </o:OLEObject></xml><! [endif]-> <math> <mrow> <mfrac> <mrow> <mn>1</mn> <mn>0</mn> </mrow> <mrow> <mn>1</mn> <mn>0</mn> <mn>0</mn> </mrow> </mfrac> <mo>×</mo> <mn>1</mn> <mn>4</mn> <mo>=</mo> <mn>0</mn> <mo>.</mo> <mn>1</mn> <mn>4</mn> <mtext> </mtext> <mtext> </mtext> <mi>g</mi> <mi>m</mi> </mrow> </math> % of Nitrogen in compound = <!- [if gte mso 9]><xml> <o:OLEObject Type="Embed" ProgID="Equation.DSMT4" ShapeID="_x0000_i1027" DrawAspect="Content" ObjectID="_1814949285"> </o:OLEObject></xml><! [endif]-> <math> <mrow> <mfrac> <mrow> <mn>0</mn> <mo>.</mo> <mn>1</mn> <mn>4</mn> </mrow> <mrow> <mn>0</mn> <mo>.</mo> <mn>2</mn> <mn>5</mn> </mrow> </mfrac> <mo>×</mo> <mn>1</mn> <mn>0</mn> <mn>0</mn> </mrow> </math> = 56%