Draw up the chemical formula of the substance and determine the mass fractions of the elements

Draw up the chemical formula of the substance and determine the mass fractions of the elements. if it consists of N and O, and the mass composition is expressed by the ratio m (N): m (O) = 7: 8

Given:
NxOy
m (N): m (O) = 7: 8

Find:
NxOy -?

Solution:
1) n (N) = m (N) / M (N) = 7/14 = 0.5 mol;
2) n (O) = m (O) / M (O) = 8/16 = 0.5 mol;
4) x: y = n (N): n (O) = 0.5: 0.5 = 1: 1;
5) Unknown substance – NO;
6) Mr (NO) = Ar (N) * N (N) + Ar (O) * N (O) = 14 * 1 + 16 * 1 = 30;
7) ω (N in NO) = N (N in NO) * Ar (N) * 100% / Mr (NO) = 1 * 14 * 100% / 30 = 46.7%;
8) ω (O in NO) = 100% – ω (N in NO) = 100% – 46.7% = 53.3%.

Answer: Unknown substance – NO; the mass fraction of N is 46.7%; O – 53.3%.