The chemical formula for the hydrogen sulfide gas that rotten eggs smell like is H2S.

The chemical formula for the hydrogen sulfide gas that rotten eggs smell like is H2S. Determine the mass fractions (%) of hydrogen and sulfur in hydrogen sulfide.

Given:
H2S

To find:
ω (H in H2S) -?
ω (S in H2S) -?

Decision:
1) Calculate the relative molecular weight of hydrogen sulfide:
Mr (H2S) = Ar (H) * N (H) + Ar (S) * N (S) = 1 * 2 + 32 * 1 = 34;
2) Calculate the mass fraction of hydrogen in hydrogen sulfide:
ω (H in H2S) = N (H in H2S) * Ar (H) * 100% / Mr (H2S) = 2 * 1 * 100% / 34 = 5.9%;
3) Calculate the mass fraction of sulfur in hydrogen sulfide:
ω (S in H2S) = 100% – ω (H in H2S) = 100% – 5.9% = 94.1%.

Answer: Mass fraction of H in H2S is 5.9%; S in H2S – 94.1%.