Question

What is the percent composition of `H_2S`?

Answer 1

`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_2S` is

`2 * 1.008gmol^-1 + 1 * 32.06gmol^-1 = 34.076gmol^-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%`