Molecular formula of organic compound

In summary, the conversation discussed the process of finding the empirical formula and molecular mass of a compound, as well as determining its structure based on the presence of a carboxylic group and double bond. The proposed compound was found to have 2 degrees of unsaturation, but further analysis showed that a second double bond needed to be added to match the alkane molecular formula.
  • #1
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Homework Statement


Screen Shot 2016-07-06 at 2.52.22 PM.png

Homework Equations

The Attempt at a Solution


Firstly I tried to find the empirical formula:

C : H : O
65.2 : 8.75 : 26.05 (mass)
5.43 : 8.75 : 1.628 (mol)
3.34 : 5.37 : 1
10 : 16 : 3
C10H16O3

This gives a molecular mass of 184.

Now with the structure: It has to contain a carboxylic group. I used trial and error and got the structure 1-hydroxyl dec-2-eneoic acid. Not sure if my naming is correct but the general idea is that there is a alcohol on one end, carboxylic acid on the other end, and a double bond in between. This means the mol of NaOH used = mol of compound Q. NaOH = 0.000237 mol. Molar mass = 0.0437 gram/0.000237 mol = 184.38 g/mol.

Does this seems correct?

Cheers!
 
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  • #2
What is the degree of unsaturation of the molecule? How many degrees of unsaturation does your proposed compound have? (Note that the problem does not require you to give a structural formula as many different structural formulas would be consistent with the observations given).
 
  • #3
According to the alkane molecular formula there are 3 degrees of unsaturation since there needs to be 22 hydrogens for a 10 carbon compound to be saturated. However, for the molecule I proposed, I only had 2 degrees of unsaturation so I need to add another double bond. I miscounted before :( Thanks!
 

Related to Molecular formula of organic compound

1. What is a molecular formula?

A molecular formula is a representation of the number and types of atoms present in a molecule. It shows the elements present in a compound and the ratio of each element in the molecule.

2. How is the molecular formula determined?

The molecular formula of an organic compound is determined by analyzing its chemical structure and the types and numbers of atoms present. This can be done through techniques such as mass spectrometry and nuclear magnetic resonance (NMR).

3. What is the difference between a molecular formula and an empirical formula?

A molecular formula shows the exact number of each type of atom in a molecule, while an empirical formula shows the simplest whole number ratio of atoms in a compound. For example, the molecular formula for glucose is C6H12O6, while the empirical formula is CH2O.

4. Can two compounds have the same molecular formula?

Yes, it is possible for two different compounds to have the same molecular formula. This is known as isomerism, where molecules have the same molecular formula but different structural arrangements.

5. How is the molecular formula used in organic chemistry?

The molecular formula is an important tool in organic chemistry as it provides information about the composition of a molecule. It is used to predict the physical and chemical properties of a compound and to determine the reactions it may undergo.

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