Find the molecular formula of the amine, the molecule of which contains

Find the molecular formula of the amine, the molecule of which contains 38.7% carbon, 45.15% nitrogen and 16.15% hydrogen, calculate its molecular weight.

Let’s implement the solution:
1. Determine the molar mass of the amine:
M (RNH2) = 38.7 + 45.15 + 16.15 = 100 g;
2. Let’s calculate the number of moles of carbon, nitrogen, hydrogen by the formula:
Y (C) = m / M = 38.7 / 12 = 3.225 mol;
Y (N) = m / M = 45.15 / 14 = 3.225 mol;
Y (H) = m / M = 16.15 / 1 = 16.15 mol;
3. The ratio C: N: H = 3.225: 3.225: 16.15 = 1: 1: 5, thus, the simplest formula of the amine is CHNH5;
4. General formula of the amine: СnH2n + 1NH2;
We find the value – n by the formula:
12n + 2 +1 + 14 + 2 = 100;
12n = 100-19;
12n = 81;
n = 6;
it follows that the molecular formula of the amine: C6H13NH2, M (C6H13NH2) = 12 * 6 + 13 + 14 + 2 = 101 g / mol, slightly exceeds.
Answer: the molecular formula of the amine: C6H13NH2 – hexylamine.