Final answer:
To determine the percentage of nitrogen in the given sample of coal, the Kjeldahl method can be used. By using the given information, it is possible to calculate the number of moles of NH3 produced and the number of moles of nitrogen in the NH3. Finally, the percentage of nitrogen in the sample of coal can be determined. The percentage of the nitrogen will be 3%.
Step-by-step explanation:
To determine the percentage of nitrogen in the given sample of coal, we can use the Kjeldahl method. According to the information provided, 1.25g of coal was used for the nitrogen estimation.
The evolved NH3 gas was collected in a conical flask containing 75mL of 0.1N sulfuric acid. To neutralize the excess acid, 25mL of 0.2N sodium hydroxide solution was required.
First, we need to calculate the number of moles of NH3 produced:
0.1 mol of H2SO4 reacts with 1 mol of NH3
0.075 mol of H2SO4 (0.1N * 0.075L) will react with X moles of NH3
Therefore, X = 0.075 mol of NH3
Next, we can calculate the number of moles of nitrogen in the NH3:
2 mol of NH3 is produced from 1 mol of N
0.075 mol of NH3 will contain X moles of N
Therefore, X = 0.0375 mol of N
Finally, to determine the percentage of nitrogen in the sample of coal:
Percentage of Nitrogen = (Mass of Nitrogen / Mass of Sample) * 100%
Mass of Nitrogen = 0.0375 mol * 14g/mol (molar mass of N)
Mass of Sample = 1.25g
Percentage of Nitrogen = (0.0375 g / 1.25 g) * 100% = 3%