# What is the percent composition of H_2S?

Apr 2, 2016

5.92% H, 94.08% S

#### Explanation:

Total mass of a compound is found by adding up the mass of all the atoms. Using mass numbers from the RSC periodic table, the total mass of the compound ${H}_{2} S$ is

$2 \cdot 1.008 g m o {l}^{-} 1 + 1 \cdot 32.06 g m o {l}^{-} 1 = 34.076 g m o {l}^{-} 1$

Percentage mass of an element in a compound is given by

M_e/M_t * 100%

where ${M}_{e}$ is the mass of all the atoms of the element and ${M}_{t}$ is the total mass of the compound.

Percentage mass of hydrogen therefore is

(2.016gmol^-1)/(34.076gmol^-1) * 100% = 5.92%

And, likewise, percentage mass of sulfur is

(32.06gmol^-1)/(34.076gmol^-1) * 100% = 94.08%