Question

What is the empirical formula of a compound that contains 50.0% carbon, 6.7% hydrogen, and 43.3% oxygen by mass?

Answer 1

`C_3H_5O_2`

Explanation:

We assume `100` `g` of unknown compound.

There are thus `(50.0*g)/(12.011*g*mol^-1)` `=` `4.163` `mol*C`.

And `(6.7*g)/(1.00794*g*mol^-1)` `=` `6.65` `mol*H`.

And `(43.3*g)/(15.999*g*mol^-1)` `=` `2.71` `mol*O`.

We divide thru by the lowest molar quantity, that of oxygen to get a formula of `C_(1.54)H_(2.45)O_(1)`, which we double to give a whole number EMPIRICAL formula of `C_3H_5O_2`.