Finding emprical formula of compound CHON

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In summary, the problem involves determining the empirical formula of a compound containing only carbon, hydrogen, nitrogen, and oxygen. Combustion of the compound produced 0.213g of CO2 and 0.0310g of H2O. In another experiment, 0.103g of the compound produced 0.0230g of NH3. Using the given information, it is possible to convert the masses of CO2, H2O, and NH3 to moles and then calculate the ratios of each element. From there, it can be determined that the empirical formula of the compound is C2H3N2O2.
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Homework Statement


a compound contains only carbon, hydrogen, nitrogen and oxygen. Combustion of 0.157g of the compound produce 0.213g of CO2 and 0.0310g of H2O. In another experiment, it is found that 0.103g of compound produces 0.0230g of NH3. What is emprical formula of the compound. Hint: Combustion involves O2. Assume all the carbon ends up in the CO2 and Hydrogen ends up in water. Also assume the Nitrogen ends up in NH3 in second experiment


Homework Equations





The Attempt at a Solution


x+ O2= CO2 +H2O

0.213g CO2/ 44gCO2= 0.0048mole of CO2
0.0310g H2O/18G H2O= 0.00172 mole of H2O
0.023g NH3/17g NH3= 0.00135 mole NH3
 
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  • #2
To start, try to express the carbon, hydrogen and nitrogen in terms of grams. You can easily convert from moles since you have already done the hard work... remember that for the nitrogen your sample size is not the same as the CH determination. Express the nitrogen as percent of total weight of the compound and then multiply the percentage by the original wt of sample used to determine CH.

Add the mass of these three elements together. Compare the answer to the starting mass. Is it the same? What is different and why?

Once you have determined the mass of the four elements, convert to moles and express the formula in the form:

C(moles C) H(moles H) N(moles N) O(moles O)

Try it from there...
 
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  • #3


Using the mole ratios, we can determine the number of moles of carbon, hydrogen, nitrogen, and oxygen present in the compound:

0.0048 mole CO2 x 1 mole C/1 mole CO2 = 0.0048 mole C
0.00172 mole H2O x 2 mole H/1 mole H2O = 0.00344 mole H
0.00135 mole NH3 x 1 mole N/1 mole NH3 = 0.00135 mole N
0.0048 mole CO2 x 2 mole O/1 mole CO2 = 0.0096 mole O

Next, we need to find the smallest whole number ratio between these moles to determine the empirical formula. In this case, it is 1:2:1:2, which means the empirical formula is CHON.
 

What is the empirical formula of a compound?

The empirical formula of a compound is the simplest whole-number ratio of atoms present in a molecule. It represents the relative number of atoms of each element in the compound.

How do you find the empirical formula of a compound?

To find the empirical formula of a compound, you need to know the mass of each element present in the compound. Then, you need to convert the mass of each element into moles and find the ratio of each element's moles. The resulting ratio will give you the empirical formula of the compound.

What is the significance of finding the empirical formula?

Finding the empirical formula is important because it helps in determining the actual composition of a compound. It also gives insight into the molecular structure and properties of the compound.

Can the empirical formula be the same as the molecular formula?

Yes, the empirical formula can be the same as the molecular formula. This happens when the compound's molecular formula is already in its simplest form, and there is no need to simplify it further.

What are some common methods for determining the empirical formula?

Some common methods for determining the empirical formula include elemental analysis, combustion analysis, and mass spectrometry. These methods involve measuring the mass of each element present in a compound and using it to calculate the empirical formula.

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