Question

A compound is 92.3% carbon and 7.7% hydrogen. What is the empirical formula of this compound?

Answer 1

`CH`

Explanation:

Follow those steps :

Imagine that you have 100 g of Carbon and hydrogen

Convert % into mass `=>`

`92.3 % -> 92.3 g`
`7.7 % -> 7.7 g`

Transform mass into moles `=>`

(The molar mass of carbon and hydrogen are rounded here)

`C: 92.3 / 12.01 = overbrace(7.69mol)^(color(blue)("3 sig. fig.")`

`H: 7.7 / 1.01 = overbrace(7.62mol)^(color(red)("3 sig. fig.")`

To see for one Carbon, how many Hydrogen you have, put the next equation `=>`

`1 / 7.69 = x / 7.62`

(It can be the other way around, for 1 Hydrogen, how many Carbon)

`1 / 7.62 = x / 7.69`

Solves for x `=>`

(Generally take the largest of those result and divide it by the smallest ) `=>`

`7.69/7.62 = 1.01~=1`

It means that for 1 Hydrogen, you have 1 Carbon each time.

Empirical formula`-=CH`