Question

What is the percent composition of `(NH_4)_2S`?

_%N?
%H?
__%S?

Answer 1

We know that the total mass is 68 amu. This is because Sulfur is 32 amu and NH4 is 18 (We have two of these compounds)

Therefore, we just find each individual elements' mass and divide by the total..

There are two nitrogen atoms, so that would be 28 amu

The percent composition would be `28/68 * 100 = 41.18%`

There are 8 hydrogen atoms, so that would be 8 amu

The percent composition would be `8/68 * 100 = 11.76%`

There is 1 sulfur atoms, so that would be 32 amu

The percent composition would be `32/68 * 100 = 47.06%`

Adding the percents should equal 100 to double check.