Question

A compuund contain c=56.8%,h=6.50%,o=28.4%n=8.28% calculate the formula

Answer 1

Out of 100 gm. of compound,

56.8 gm of C, i.e., about 4.8 mol of C (atomic mass of C = 12 u)

6.5 gm of H, i.e., 6.5 mol of H (atomic mass of H = 1 u)

28.4 gm. of O, i.e., about 1.8 mol of O (atomic mass of O = 16 u)

8.28 gm of N, i.e., 0.6 mol of N (atomic mass of N = 14 u)

Calculating the ratios of C, H, O and N in the compound

C : H : O : N is 8 : 11 : 3 :1.

Thus, Empirical formula --> C8H1103N

Answer 2

Concept:

The mole concept relates to a mole's atomic mass, which is measured in grams. A mole is the grams of the atomic mass of an element. The idea of a mole combines the mass of a single atom or molecule in a.m.u. with the mass of a large group of equivalent molecules in grams.

Given:

C = 56.8%

H = 6.50%

O = 28.4%

N = 8.28%

Find:

Calculate the molecular formula of the unknown compound.

Solution:

The mass of C = 56.8 g

The mass of H = 6.50 g

The mass of O = 28.4 g

The mass of N = 8.28 g

We know that,

The molar mass of carbon = 12 g/mol

The molar mass of hydrogen = 12 g/mol

The molar mass of oxygen = 12 g/mol

The molar mass of nitrogen = 12 g/mol

Now, the number of moles (n) can be calculated as:

               n = Mass /  Molar mass

n(C) = 56.8 g / 12 g/mol = 4.7 mol

n(H) = 6.50 g / 1 g/mol = 6.5 mol

n(O) = 28.4 g / 16 g/mol = 1.8 mol

n(N) = 8.28 g / 14 g/mol = 0.6 mol

To make the whole number we have to multiply them by 2 and we get,

n(C) = 4.73 mol * 2 = 9.4 mol = 9

n(H) = 6.5 mol * 2 = 13 mol = 13

n(O) = 1.8 mol * 2 = 3.6 mol = 4

n(N) = 0.6 mol * 2 = 1.2 mol = 1

Hence, the molecular formula of the cimpound is C₉H₁₃O₄N₁.

#SPJ2