Question

an organic compound contains 58.55% carbon 4.05% hydrogen and 11.36% nitrogen determine its molecular formula if its molecular weight is 123

Answer 1

Answer:

C5H5NO2

Explanation:

molecular weight/(empirical weight)=n

Answer 2

Answer:

Explanation:

Let the total mass = 100 grams.

Thus, the mass of each element is equal to the given percentage

Mass of C = 40.65 g

Mass of H = 8.55 g

Mass of N = 23.77 g

Mass of O = 100 - 72.97 = 27.03 g

Molar mass of C = 12 g/mole

Molar mass of H = 1 g/mole

Molar mass of N = 14 g/mole

Molar mass of O = 16 g/mole

Thus, converting masses into moles and for mole ratio, dividing each value of moles by the smallest number of calculated moles -

C = 40.65 / 12 = 3.3875 --- 3.3875/1.6929 = 2.001

H =  8.55 /1 = 8.55 --- 8.55/1.6929 = 5.0505

N = 23.7 / 14 = 1.6929 --- 1.6929 /1.6929 =1

O =  27.1 / 16 = 1.6938 --- 1.6938/1.6929 = 1.005

Thus the empirical formula will be = C2 H5 NO

Mass empirical formula =2 (12) + 5 (1) + 1 (14) + 1(16) = 59

Given molecular mass = 2 x vapour density = 2 x 29.5 = 59

n = Molecular mass / Empirical mass

= 59 /59 = 1

Molecular formula = Empirical formula x n

= C2 H5 NO x 1

= C2 H5 NO