Chemistry

posted by .

An unknown compound contains carbon, hydrogen, and oxygen. When burned, a 2.000 gram sample of this compound releases 3.451 g of carbon dioxide and 1.059 grams of water. What is the empirical formula of this compound?

Thank you very much.

  • Chemistry -

    Convert g CO2 to g C and g H2O to g H. Add grams C and grams H and subtract from total mass to find grams oxygen.

    Convert g C, g H, g O to moles.
    moles = grams/molar mass

    Then find the ratio of the elements to each other. I worked the Na2S2O3 problem for you earlier; this one is done the same way to find the empirical formula. Post your work if you get stuck.

  • Chemistry rework problem -

    Thank you Dr. Bob222

    An unknown compound contains carbon, hydrogen, and oxygen. When burned, a 2.000 gram sample of this compound releases 3.451 g of carbon dioxide and 1.059 grams of water. What is the empirical formula of this compound?

    Here is the problem I worked out:
    C=.94118 gC
    H=.1177 gH
    O=2.00-3.451-1.059 = .392

    if i divide everything by .1177, i get

    c=7.996
    H=1.00
    O=3.3305

    Now, I am stuck on how to get the ratios and final answer

  • Chemistry -

    First, you made an error before you get to that part.
    grams O = 2.00-grams C - grams H. You subtracted grams CO2 and grams H2O. Your grams C (and moles) is ok as is the grams H (and moles H) but the oxygen must be redone.

  • Chemistry -

    Okay, so my O=.82348

    then I divide everything by .1177, and i get

    c=7.996
    H=1.00
    O=6.99

    This looks like a ratio of 8:1:7

    C8H107??

  • Chemistry -

    No, it looks like 8:1:7 to me but I don't think that is right.
    I have C = 0.9421g (close enough to your answer) and H = 0.1176g (close enough to your answer) so O is
    2.000 - 0.9421 - 0.1176 = 0.9403 g O (the slight differences in our C and H won't account for this difference in your value and mine. I've checked mine; perhaps you should check yours.
    Then
    0.9421/12 = 0.0785 moles C
    0.1176/1 = 0.1176 moles H
    0.9403/16 = 0.05877 moles O

    0.05877/0.05877 = 1 for O
    0.1176/0.05877 = 2 for H
    0.0785/0.05877 = 1.33 for C and these aren't whole numbers. You can quickly see that multiplying all by 2 won't work because 1.33 becomes 2.66; however, multiplying by 3 should get it.
    O = 1*3 = 3
    H = 2*3 = 6
    C = 1.33*3 = 3.99 which rounds to 4.00
    I would write C4H6O3 for the empirical formula.
    Check my work.

  • Thank you DrBob222 -

    Thank you - you are an awesome teacher!!!!!

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. Chemistry

    Please check my answers for the following questions. THANK YOU. 1) The empirical formula of a compound that is 25.9% nitrogen and 74.1% oxygen is.... ANSWER: N2O 2) empirical formula of a compound that consists of 4.80 grams of carbon, …
  2. C hemistry

    An unknown compound contains only carbon, hydrogen, and oxygen . Combustion of 2.50 g of this compound produced 3.67 g of carbon dioxide and 1.50 g of water. What is the empirical formula of a substance that contains 8.33×10−2 …
  3. chemistry

    A 25g sample of a compound composed of Carbon, Hydrogen, and Oxygen was combusted. 55grams of Carbon Dioxide and 30 grams of water were collected. A) What is the empirical formula of the compound?
  4. Chemistry

    The molecular formula of a compound containg only carbon and hydrogen is to be determined. When a sample of the compound is burned on oxygen gas, 7.2 grams of water and 7.2 liters of carbon dioxide gas are produced(measured at STP). …
  5. Chemistry

    A certain compound contains carbon, hydrogen , and oxygen. When 1.00 grams of this compound are burned in oxygen gas 1.47 grams of CO2 and 0.600 grams of water are formed. When 2.75 grams of the compound are dissolved in 10.0 grams …
  6. Chemistry

    A certain compound contains carbon, hydrogen , and oxygen. When 1.00 grams of this compound are burned in oxygen gas 1.47 grams of CO2 and 0.600 grams of water are formed. When 2.75 grams of the compound are dissolved in 10.0 grams …
  7. chemistry

    8750 g of a compound which contains only carbon, hydrogen, and nitrogen were burned in oxygen to produce, 2.1930 g of N2O4 , and 2.2900 g of water. What is the empirical formula of the compound?
  8. Chemistry

    A 3.000 gram sample of an unknown compound containing the elements carbon, hydrogen, and nitrogen is analyzed by combustion. The combustion releases 4.714 grams of carbon dioxide and 1.500 grams of nitrogen. If 25 molecules have a …
  9. chemistry

    a compound contains 5.2% by mass Nitrogen. It also contains carbon, hydrogen and oxygen. Combustion of 0.085g of the compound produced 0.224g of carbon dioxide and 0.0372g of water. Calculate the empirical formula of the compound.
  10. Chemistry

    An Unknown Compound (M=60.09 g/mol) is composed of Carbon, Hydrogen and Oxygen. Combustion of 0.255 g of the unknown compound produces 0.561 g Carbon Dioxide and 0.306 g of Water. Determine the molecular formula of the compound.

More Similar Questions