Question

How would you determine what compound has the highest percent by mass of hydrogen?

For example of these compounds:
`HCl`
`H_2O`
`H_2SO_4`
`H_2S`
`HF`

Answer 1

Of the compounds listed in the question, water has the highest percent mass of hydrogen.

Explanation:

Divide the mass of hydrogen in each compound by the molar mass of the compound and multiply by 100. In the calculations below, I have rounded the masses to whole numbers. Also, the numerators are the mass of hydrogen in the compound in grams, and the denominators are the molar masses of the compounds in grams.

`"mass percent H"="mass H"/"mass compound"xx100`

`"HCl:"` `1/36xx100="2.8%` `"H"`

`"H"_2"O":` `2/18xx100="11.1%` `"H"`

`"H"_2"SO"_4":` `2/98xx100=2.0%` `"H"`

`"H"_2"S":` `2/34xx100=5.9%` `"H"`

`"HF":` `2/21xx100=9.5%` `"H"`