Set the formula for the limiting primary amine, the mass fraction of carbon in which is 53, 33%.

Given:
The general formula for the limiting primary amine is CnH2n + 3N
ω (C in CnH2n + 3N) = 53.33%

To find:
CnH2n + 3N -?

Decision:
1) Mr (CnH2n + 3N) = N (C in CnH2n + 3N) * Ar (C) * 100% / ω (C in CnH2n + 3N) = n * 12 * 100% / 53.33% = 1200n / 53 , 33;
2) Mr (CnH2n + 3N) = Ar (C) * N (C) + Ar (H) * N (H) + Ar (N) * N (N) = 12 * n + 1 * (2n + 3) + 14 * 1 = 14n + 17;
3) 1200n / 53.33 = 14n + 17;
1200n = 746.62n + 906.61;
453.38n = 906.61;
n = 2;
4) The formula of the limiting primary amine is C2H7N – C2H5-NH2 – ethylamine.

Answer: The formula of the limiting primary amine is C2H7N – C2H5-NH2 – ethylamine.