Question

Analysis of an unknown sample indicated the sample contained 0.140 grams of N and 0.320 grams of O. The molecular mass of the compound was determined to be 92.02 amu. What is the molecular formula of the compound?

Answer 1

the molecular formula of the compound is N2O4

Step-by-step explanation:

- Find the empirical formula

mole of N present = mass of N divided by molar mass of N = 0.140/14 = 0.01 mole

mole of O present = mass of O divided by molar mass of O = 0.320/16 = 0.02 mole

Divide both by the smallest number of mole to determine the coefficient of each, the smallest number of mole is 0.01 thus:

quantity of N = 0.01/0.01 = 1

quantity of O = 0.02/0.01= 2

thus the empirical formula = NO2

- Now determine the molecular formula by finding the ratio of molecular formula and empirical formula

Molar mass of molecular formula = 92.02 amu = 92.02 g/mole

Molar mass of empirical formula NO2 = (14 + (16 x 2)) = 46 g/mole

the x factor = 92.02/46 = 2

Molecular formula = 2 x NO2 = N2O4