Question

In an organic compound Carbon, Hydrogen and Oxygen are 60%, 13.33% and 26.66%
respectively. Find molecular formula if the molecular mass of compound is 60.​

Answer 1

The ratio of the number of gram atoms among C, H, N and O is,

C:H:N:O=  

12 /20  :  1 /6.67 :  14 /46.67 :  16 /26.66

=1:4:2:1

Empirical formula =CH  4  N 2  O

So, empirical weight =60 g.

Given, molecular weight =60 g.

Molecular formula=(Empirical formula)  n

​  

n= Empirical weight /Molecular weight =  60 /60  =1

So, molecular formula is (NH  2 ) 2  CO

Hope this helped

Answer 2

The molecular formula of the compound is  C3H8O.

Given: Percentage of Carbon = 60 %,

           Percentage of Hydrogen = 13.33 %,

           Percentage of Oxygen = 26.66 %,

           The molecular mass of the compound = 60.

To Find: Molecular formula of the compound.

Solution:

• We need to find the moles of each of the constituents first and then divide it with the smallest molar quantity to get the empirical formula.
• Next, we need to find the formal mass and divide the total molecular mass with it to get n which shall give us our molecular formula.

The total molecular mass of the compound = 60.

Percentage of Carbon = 60

So, the number of moles of Carbon = 60 / 12

                                                     = 5

Percentage of Hydrogen = 13.33

So, the number of moles of Hydrogen = 13.33 / 1

                                                         = 13.33

Percentage of Oxygen = 26.66

So, the number of moles of Oxygen = 26.66 / 16

                                                      = 1.67

Now, the smallest molecular quantity = 1.67

Now, we shall divide the number of moles of all the constituent elements with this smallest molecular quantity to get the empirical formula,

So, for Carbon, value = 5 / 1.67 ≅ 3

     For Hydrogen, value = 13.33 / 1.67 ≅ 8

     For Oxygen, value = 1.67 / 1.67 ≅ 1

So, the empirical formula of the compound is C3H8O.

Formal mass of the compound = 12 × 3 + 1 × 8 + 16

                                                    = 60

So, the value of n = Total molecular mass / Formal mass

                       = 60 / 60

                       = 1

So, the molecular formula of the compound is  C3H8O.

Hence, the molecular formula of the compound is  C3H8O.

#SPJ3