chemistry

Ibuprofen, the active ingredient in advil, is made up of carbon, hydrogen, and oxygen atoms. When a sample of ibuprofen, weighing 5.000 g, burns in oxygen, 13.86 g of CO2 and 3.926 g of water are obtained. What is the simplest formula of ibuprofen?

My work:
13.86 g CO2/ 12.01 g C= 1.15 g C
3.926 g H2O/ 2.02 = 1.94 g H
13.86 g CO2 + 3.926 g H2O = 17.48sub6 g products
17.48sub6 g - 3.09 = 14.40 g O
1.15 g C x 1mol/12.01 g= .0957sub5 mol C
1.94 g H x 1mol/1.01 g= 1.92sub0 mol H
14.40 g O x 1mol/16.00= .9000 mol O
divide all by .0957sub5...
the formula comes out to C10H201O94
My problem is, the 14.40 g O isn't just the oxygen in the ibuprofen, but the oxygen in the combustion as well. how do I find out just what's in the ibuprofen so I get the correct formula?


Your work is wrong.

To get the grams of C in CO2, find the fraction of C in CO2, which is 12/(12+2*16)= 12/40
Then, grams C= 13.86 * 12/40 g C
then moles C= gramsC/12

Do the same with H.
Then, to find O, add the grams H and grams C, subtract them from 5.000. Then figure the grams O, and moles O.

Now, having moles of all, do this.
moles C xxxx
moles H yyyy
moles O zzzz

take the smallest of the three numbers, and divide it into all the numbers to get a whole number ratio.

example
moles C 4.53
moles H 9.05
moles O 12.22

divide all by 4.53
moles C 1
moles H 2
moles O 3
CH2O3 in this example. Here is another more complicated:
moles C 4.53
moles H 11.35
moles O 12.22
divide,
moles C 1
moles H 2.5
moles O 3
Now here, to get a whole number ratio , double the numbers..
moles C 2
moles H 5
moles O 6
C2H5O6



Thank you, I assumed something was wrong when I didn't end up using the 5.000 g in my calculation.
I've used this set-up before, and for this problem after doing it this way, I received C101H70O20. This doesn't seem right to me. I think any error I have might have occurred around here:
moles C= .3149sub 2
moles H= .217sub 8
moles O= .0623sub 6
I divided everything by .0623sub 6 [smallest number] and got
moles C= 5.05
moles H= 3.5
moles O= 1
and multiplied everything by 20 to get a whole number ratio.
The molar masses I used for all my calculations:
12.01 g/mol = C
1.01 g/mol = H
16.00 g/mol = O
Did I make an error, or is this correct?


Thank you, I assumed something was wrong when I didn't end up using the 5.000 g in my calculation.
I've used this set-up before, and for this problem after doing it this way, I received C101H70O20. This doesn't seem right to me. I think any error I have might have occurred around here:
moles C= .3149sub 2 OK to here,
moles H= .217sub 8 There are 2 mols H in H2O. This will change mols H as well as grams H AND grams oxygen.
moles O= .0623sub 6
I divided everything by .0623sub 6 [smallest number] and got
moles C= 5.05
moles H= 3.5
moles O= 1
and multiplied everything by 20 to get a whole number ratio.
The molar masses I used for all my calculations:
12.01 g/mol = C
1.01 g/mol = H
16.00 g/mol = O
Did I make an error, or is this correct?
See comments at H line.

  1. 👍
  2. 👎
  3. 👁
  1. im getting that the moles C = .347
    moles H = .436
    moles O = 0.025

    and getting a formula of C14H17O
    However, i looked it up on wiki and saw that the formula for ibuprofen is in fact i C13H18O2.
    the C/H discrepancy is understandable, but the O2 to O is not. Could i have missed something that leads to a doubling of the moles O?

    1. 👍
    2. 👎

Respond to this Question

First Name

Your Response

Similar Questions

  1. science

    1. Which statement is true about the following molecule? (1 point)The molecule is composed of four atoms.The molecule contains oxygen atoms.The molecule is water.The molecule represents an element. 2. A(n) _____________ is made up

  2. Science

    1. Glucose is a simple sugar made up of carbon, hydrogen, and oxygen. What kind of molecule is glucose? A) Glucose is protein B) Glucose is a nucleic acid*** C) Glucose is an organic molecule D) Glucose is an inorganic molecule 2.

  3. science

    Which process in photosynthesis uses energy from the sun? absorbing carbon dioxide releasing oxygen combining carbon dioxide and hydrogen splitting water into hydrogen and oxygen

  4. science

    All biomolecules are made up of the elements carbon, hydrogen, nitrogen, oxygen, and sulfur. carbon, hydrogen, nitrogen, and oxygen. carbon, hydrogen, oxygen, and sulfur. carbon, hydrogen, and oxygen.*** Nucleic acids are the

  1. Science

    If a chemical reaction such as photosynthesis begins with 6 atoms of carbon (C), how many atoms of carbon (C) should be in the products? A) 2 atoms of carbon (C) B) 3 atoms of carbon (C) C) 6 atoms of carbon (C)**** D) 12 atoms of

  2. Biology

    1. Which elements are most abundant in living organisms? A. hydrogen, carbon, calcium, potassium, oxygen, and phosphorus B. oxygen, calcium, phosphorus, sodium, hydrogen, and carbon C. carbon, potassium, iron, magnesium, hydrogen,

  3. PLZ HELP FAST Science

    Which process in photosynthesis uses energy from the sun? (1 point) absorbing carbon dioxide splitting water into hydrogen and oxygen combining carbon dioxide and hydrogen releasing oxygen PLEASE I NEED TO GET THIS DONE TODAY!!!

  4. biology

    Choose the total number of each item requested below. 4C6H12O6 Carbon atoms Hydrogen atoms Oxygen atoms Molecules

  1. Science Matter and Energy Unit Test plz help ASAP

    Which process in photosynthesis uses energy from the sun?(1 point) splitting water into hydrogen and oxygen releasing oxygen combining carbon dioxide and hydrogen absorbing carbon dioxide Plz anybody help me for the whole test?

  2. chemistry

    Question 1. A Compound Containing 3 Atoms Of Carbon & 8 Atoms Of Hydrogen Is Combined In A Reaction With Oxygen Molecules. The 2 End Products Of This Equation Are Carbon Dioxide &water. What Element Should You Look At 1st In

  3. Science

    A molecule of ethanol has two carbon atoms, six hydrogen atoms, and one oxygen atom. A ball-and-stick model of ethanol is made from the following components: -One red ball -Two black balls -Six white balls -Eight sticks What do

  4. Chemistry

    A compound containg 3 atoms of carbon and 8 atoms of hydrogen is combined in a reaction with oxygen molecules. The two end products of this equation are carbon dioxide (CO2) and water. What element should you look at first in

You can view more similar questions or ask a new question.