The amount of nitrogen in an organic substance can be determined by an analytical method called the Kjeldahl method, in which all the nitrogen in the organic substance is converted to ammonia. The ammonia, which is a weak base, can be neutralized with hydrochloric acid, as described by the equation NH3(aq)+HCl(aq)⟶NH4Cl(aq) NH3(aq)+HCl(aq)⟶NH4Cl(aq) If 88.0 mL88.0 mL of 0.150 M HCl(aq)0.150 M HCl(aq) is needed to neutralize all the NH3(g)NH3(g) from a 2.25 g sample of organic material, calculate the mass percentage of nitrogen in the sample.

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Аноним Аноним · Answer 1 · 2019-10-24T06:36:59+02:00

Answer: The mass percent of nitrogen in the sample is 8.2 %

Explanation:

Kjeldahl method is defined as the analytical method which is used in the determination of nitrogen content in any organic compound.

In this method, nitrogen is converted into ammonia and the ammonia formed is then reacted with an acid.

The chemical equation for the reaction of ammonia with hydrochloric acid follows:

[tex]NH_3(aq.)+HCl(aq.)\rightarrow NH_4Cl(aq.)[/tex]

To calculate the percentage of nitrogen in the organic compound, we use the equation:

[tex]\% \text{ nitrogen in sample}=\frac{(1.4\times M_1V_1)}{w}[/tex]

where,

[tex]M_1[/tex] = molarity of acid used = 0.150 M

[tex]V_1[/tex] = Volume of acid used (in mL) = 88.0 mL

w = mass of sample = 2.25 g

Putting values in above equation, we get:

[tex]\% \text{ nitrogen in sample}=\frac{(1.4\times 0.150\times 88.0)}{2.25}\\\\\% \text{ nitrogen in sample}=8.2\%[/tex]

Hence, the mass percent of nitrogen in the sample is 8.2 %