Ask Me Help Desk

Ask Me Help Desk (https://www.askmehelpdesk.com/forum.php)
-   Chemistry (https://www.askmehelpdesk.com/forumdisplay.php?f=68)
-   -   Empirical formula (https://www.askmehelpdesk.com/showthread.php?t=530146)

  • Nov 29, 2010, 05:24 PM
    susus
    Empirical formula
    A compound is known to contain only carbon, hydrogen, and oxygen. If the complete combustion of a 0.150-
    G sample of this compound produces 0.225 g of CO2 and 0.0614 g of H2O, what is the empirical formula of
    This compound?A compound is known to contain only carbon, hydrogen, and oxygen. If the complete combustion of a 0.150-
    G sample of this compound produces 0.225 g of CO2 and 0.0614 g of H2O, what is the empirical formula of
    This compound?

    I got the moles of CO2 and H2O ,
    I did not know how to continue..
    It was the only question of the 150 questions I did not solve right ! Haha
  • Nov 29, 2010, 06:17 PM
    susus
    I got it...
    !

    0.225 g CO2 x (12.01/44.01) = 0.0614 g C
    0.0614 g H2O x (2.02/18.02) = 0.00688g H

    0.150 -(0.0614 + 0.00688)g = 0.0817g O

    Now, divide each weight by the atomic mass of the respective element.This will give a set of numbers proportional to the empirical formula.

    0.0614/12.01 = 0.00511
    0.00688/1.01 = 0.00681
    0.0817/16.00 = 0.00511

    Now, we need to get in whole numbers we will divide all of them by the smallest value (it is a good starting point)

    0.00511/0.00511 = 1.00 C
    0.00681/0.00511 = 1.33 H
    0.00511/0.00511 = 1.00 O

    Now we will multiply all of them by 3 to get all as whole numbers:

    So the empirical formula is C3H4O3

    ;)
  • Nov 29, 2010, 08:18 PM
    DrBob1
    Good,work!

  • All times are GMT -7. The time now is 07:00 AM.