With the complete combustion of an amine weighing 9 g, 17.6 g of carbon dioxide, 12.6 g of water

With the complete combustion of an amine weighing 9 g, 17.6 g of carbon dioxide, 12.6 g of water, 2.8 g of nitrogen were formed. The vapor density of the amine in air is 1.55. Derive the molecular formula of the amine. Make up all possible structural formulas of amines and name the substances.

1.Let’s find the mass of carbon atoms in 17.6 g of carbon dioxide.

44 g – 12 g (C),

16.5 g-m (C).

m = (17.6 × 12): 44,

m = 4.8 g.

2.Let’s find the mass of hydrogen atoms in 12.6 g of water.

Мr (Н2О) = 18 g / mol.

18 g – 2 g (H),

12.6 g-m (H).

m = (12.6 × 2): 18,

m = 1.4 g.

3.Let’s find the mass of nitrogen atoms in 2.8 g of N2.

M (N2) = 28g / mol.

28 g – 28 g

2.8 g – x,

x = 2.8 g.

Let’s find the amount of substance of atoms of carbon, hydrogen, nitrogen.

n = m: M.

M (C) = 12 g / mol.

n (C) = 4.8 g: 12 g / mol = 0.4 mol.

M (H) = 1.4: 1 = 1.4 mol.

M (N) = 2.8: 14 = 0.2 mol.

Let’s find the ratio of the amounts of the substance carbon and hydrogen.

C: H: N = = 0.4: 1.4: 0.2 = 2: 7: 1.

Let’s find the molar mass of the hydrocarbon by the relative density.

Relative density is given by air. You need to multiply the molar mass of air (29) by 1.55.

D (air) = 1.55 × 29 = 45.

The molar mass of the hydrocarbon is 45. Let’s define the formula.

C2H5NH2 – ethylamine.

CH3 – NH – CH3 – diethylamine.