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

Dec 17, 2015

$C H$

#### Explanation:

Imagine that you have 100 g of Carbon and hydrogen

Convert % into mass $\implies$

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

Transform mass into moles $\implies$

(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 $\implies$

$\frac{1}{7.69} = \frac{x}{7.62}$

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

$\frac{1}{7.62} = \frac{x}{7.69}$

Solves for x $\implies$

(Generally take the largest of those result and divide it by the smallest ) $\implies$

$\frac{7.69}{7.62} = 1.01 \cong 1$

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

Empirical formula$\equiv C H$