Name: All About Analytical Chemistry
Uploaded: 2019-07-19
Duration: 3 min 40 s
Description: This video will tell us about the methods to separate substances and the instruments used in this process. Let's watch the video to study qualitative and qua...

Question

An organic compound containing oxygen, carbon, hydrogen and nitrogen contains

20 %

carbon,

6.7 %

hydrogen and

46.67 %

nitrogen. Its molecular mass was found to be

60

. Find the molecular formula of the compound.

Accepted Answer

Given,

Percentage of carbon, hydrogen and nitrogen are $20 %, 6.7 %$ and $46.67 %$ respectively.

Molar mass of the compound $= 60 g {mol}^{- 1}$

To find the molecular formula of the compound:

$% C + % H + % N = 20 + 6.7 + 46.67 = 73.37 %$ and this is less than $100 %$ .

Hence, the compound contains adequate oxygen so that the total percentage of elements is $100 %$ .

Hence, percentage of oxygen $= 100 - 73.37 = 26.63$

Moles of $C = \frac{% of C}{Atomi mass of C}$ $= \frac{20}{12} = 1.667 mol$

Moles of $20 %$

Moles of $N = \frac{% of N}{Atomi mass of N} = \frac{46.67}{14} = 3.334 mol$

Moles of $O = \frac{% of O}{Atomi mass of O} = \frac{26.63}{16} = 1.664 mol$

Hence, the ratio of number of moles of $C : H : N : O$ is $\frac{1.667}{1.664} = 1, \frac{6.700}{1.664} = 4, \frac{3.334}{1.664} = 2$ and $\frac{1.664}{1.664} = 1$

Hence, empirical formula is ${CH}_{4} N_{2} O$ . Empirical formula mass $= 12 + 4 + 28 + 16 = 60 g {mol}^{- 1}$ .

$n = \frac{Molecular mass}{Empirical formula mass} = \frac{60}{60} = 1$

Molecular formula $= {(Empirical formula)}_{n}$ $= {({CH}_{4} N_{2} O)}_{1} = {CH}_{4} N_{2} O$

Thus, molecular formula of the compound is ${CH}_{4} N_{2} O$ .

An organic compound containing oxygen, carbon, hydrogen and nitrogen contains $20 %$ carbon, $6.7 %$ hydrogen and $46.67 %$ nitrogen. Its molecular mass was found to be $60$ . Find the molecular formula of the compound.

Important Questions on Introduction to Analytical Chemistry

Learn and Prepare for any exam you want !

An organic compound containing oxygen, carbon, hydrogen and nitrogen contains 20 % carbon, 6.7 % hydrogen and 46.67 % nitrogen. Its molecular mass was found to be 60. Find the molecular formula of the compound.

Important Questions on Introduction to Analytical Chemistry

Learn and Prepare for any exam you want !

An organic compound containing oxygen, carbon, hydrogen and nitrogen contains $20 %$ carbon, $6.7 %$ hydrogen and $46.67 %$ nitrogen. Its molecular mass was found to be $60$ . Find the molecular formula of the compound.