i'm having trouble figuring out my unknown compound.
The elemental analysis is 87.28%carbon and 12.72% hydrogen for my unknown liquid, and for my solid unknown the elemental analysis is 79.22% carbon and 5.7% hydrogen and 15.98% oxygen.
I'm not able to figure out the molecular formula for both.Please help!
I can help you get the empirical formula for each.
1) assume you have a sample of 100 g
then 87.28 grams of C, or xxx moles of C
and 12.72 g of H, or yyyy moles of H
Now whichever number of moles is the least, divide that into each xxxx and yyyy. The whole number is the subscripts in the empirical formula. If you do not get a whole number ratio, multiply each number by a common factor until you get a whole number ratio.
I get in my head C4H7 for the empirical formula.
Do the same technique for the second compound
To get the molecular formula from the empirical formula, you need more information.
thanks 4 the help
i have the empirical formula,but i'm not able to get the molecular formula.
Please help
You need more information to obtain the molecular formula. Did you do a freezing point depression to obtain an approximate molar mass? Or some other experiment to determine the approximate molar mass.
To determine the molecular formula of a compound based on its elemental analysis, you need to gather more information about the compound. Elemental analysis provides the relative quantities of different elements in a compound but does not give the specific arrangement of atoms within the molecule.
To find the molecular formula, you would typically need additional data such as the molar mass of the compound or its molecular weight. Without this information, it becomes difficult to determine the exact molecular formula. However, we can still provide some possible suggestions based on the given elemental analysis.
Let's consider the unknown liquid first: With 87.28% carbon and 12.72% hydrogen, we can assume that the compound contains only carbon and hydrogen. To calculate the empirical formula, we need to convert the percentages to mole ratios.
Assuming we have a 100g sample of the liquid, we have:
- Carbon: (87.28/12.01) = 7.26 moles
- Hydrogen: (12.72/1.01) = 12.6 moles
To find the simplest whole number ratio between the elements, we divide both values by the smaller one (7.26 in this case):
- Carbon: 7.26 / 7.26 = 1
- Hydrogen: 12.6 / 7.26 ≈ 1.73
Now, multiply both ratios by 2 to obtain whole numbers:
- Carbon: 1 x 2 = 2
- Hydrogen: 1.73 x 2 = 3.46 ≈ 3
Based on this calculation, the empirical formula for the unknown liquid could be CH2 or approximately C2H4. However, remember that without additional information, this is just a suggestion.
Now, let's move on to the solid unknown compound: With 79.22% carbon, 5.7% hydrogen, and 15.98% oxygen, we can assume that the compound contains carbon, hydrogen, and oxygen. Again, we need to convert the percentages to mole ratios.
Assuming we have a 100g sample of the solid, we have:
- Carbon: (79.22/12.01) = 6.59 moles
- Hydrogen: (5.7/1.01) = 5.64 moles
- Oxygen: (15.98/16.00) = 0.999 moles
To find the simplest whole number ratio, we divide all values by the smallest one (0.999 moles of oxygen):
- Carbon: 6.59 / 0.999 ≈ 6.6
- Hydrogen: 5.64 / 0.999 ≈ 5.64
- Oxygen: 0.999 / 0.999 = 1
Based on this calculation, the empirical formula for the solid unknown could be C6.6H5.64O or approximately C7H6O, considering we should have whole number ratios.
Remember that without more specific information about the compound's structure or its molar mass, it is difficult to determine the exact molecular formula. The suggested formulas are empirical formulas that provide a starting point for further investigations or analyses.