Question

0.90g of an organic compound containing only carbon, hydrogen, and nitrogen on combustion gave 1.1g of CO2 and 0.3g water. What is the %C , %H and %N in the organic compound?
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Answer 1

Answer:

Percentage composition of Carbon is 33.33 %, of Hydrogen is 3.66 % and that of Nitrogen is 63 %.

Explanation:

We are given:

Mass of H20 = 0.3 g

Mass of CO2 = 1.1 g

Molar mass of H2O  = 18 g/mol

Molar mass of CO2  = 44 g/mol

For H2O

In 18 g of water, amount of hydrogen present is 2 grams

So, in 0.3 g of water, amount of hydrogen present will be

\frac{2} {18}\times 0.3= 0.03 of hydrogen

For CO2

In 44 g of carbon dioxide, amount of carbon present is 12 grams

So, in 1.1 g of carbon dioxide, amount of carbon present will be \frac {12} {44}\times 1.1 = 0.3 g of carbon.

Mass of nitrogen in compound = (0.9 - 0.3 - 0.033) = 0.567 g

To calculate the percentage composition of an element in compound, the formula used is:

f=%5C%25%5Ctext%7B%20composition%20of%20Hydrogen%7D%3D%5Cfrac%7B0.033%7D%7B0.9%7D%5Ctimes%20100%3D3.66%5C%25%5C%5C%5C%5C%5C%25%5Ctext%7B%20composition%20of%20Carbon%7D%3D%5Cfrac%7B0.3%7D%7B0.9%7D%5Ctimes%20100%3D33.33%5C%25%5C%5C%5C%5C%5C%25%5Ctext%7B%20composition%20of%20Nitrogen%7D%3D%5Cfrac%7B0.567%7D%7B0.9%7D%5Ctimes%20100%3D63%5C%25

Hence, the percentage composition of Carbon is 33.33 %, of Hydrogen is 3.66 % and that of Nitrogen is 63 %.