Finding element X in an unknown compound

  • Thread starter Saracen Rue
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In summary, the unknown compound has a mass of 1.023 kg and it is composed of elements that have a molar mass of 240.5 g/mol. Element X is not one of the elements in the compound.
  • #1
Saracen Rue
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Homework Statement


An unknown compound weighs 1.023 kg. It is known that element X composes 28.3% of the compound. Given that the molar mass is 240.5 g/mol, find element X.

Homework Equations


mole = mass / atomic weight
(n = m / Ar)

mole = mass / molecular weight
(n = m / Mr)

mole = number of particles / Avogadro's number
(n = P / NA)

The Attempt at a Solution


I tried solving using the first equation, but I don't know them mass, Ar or mole of element X. I solved for the mole of the substance using the second equation, but I don't know how to find the unknown element from there. I don't think the last equation is applicable in this particular case, but I included it just in case.
 
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  • #2
Neither of the equations you listed is applicable here, answer is much more trivial.

Pretty basic math: you are being told x grams compose 28.3% of 240.5 g. How many grams is x?

Not that I know what the final answer is. Unless you did some mistake copying numbers, there is no element that fits.
 
  • #3
Borek said:
Neither of the equations you listed is applicable here, answer is much more trivial.

Pretty basic math: you are being told x grams compose 28.3% of 240.5 g. How many grams is x?

Not that I know what the final answer is. Unless you did some mistake copying numbers, there is no element that fits.

I think I've worked out the problem. 28.3% of 240.5 g isn't actually giving the Ar of the element - it's giving the Ar of the element x the number of said element in the compound. I can't work out how I could find just the Ar on its own, without the number of the element factoring into the problem.
 
  • #4
The only valid approach is to guess - assume there is a single atom, or two atoms, or three atoms per molecule and so on. Sadly, none of the numbers you will get gives a reasonable answer.
 
  • #5
And then the first sentence of all makes no sense, and on any near guess as to sense it is irrelevant... I don't think we should try to guess further.
 

1. How can I determine the chemical formula of an unknown compound?

The best way to determine the chemical formula of an unknown compound is through a combination of techniques such as elemental analysis, spectroscopy, and chromatography. These techniques can provide information about the elements present in the compound, their relative proportions, and the functional groups present.

2. What is the role of mass spectrometry in finding element X in an unknown compound?

Mass spectrometry is a powerful analytical technique that can be used to identify and quantify the elements present in a compound. By measuring the mass-to-charge ratio of ionized molecules, mass spectrometry can provide information about the molecular weight and composition of a compound, which can help identify the presence of element X.

3. Can nuclear magnetic resonance (NMR) spectroscopy be used to find element X in an unknown compound?

Yes, NMR spectroscopy is a valuable tool in determining the structure and composition of unknown compounds. By analyzing the chemical shifts and coupling patterns of nuclei in a molecule, NMR can provide information about the types and number of atoms present, including element X.

4. Is it possible to find element X in an unknown compound without using expensive equipment?

While some techniques, such as mass spectrometry and NMR spectroscopy, do require specialized and expensive equipment, there are also simpler methods that can be used to identify elements in unknown compounds. These include simple chemical tests, such as flame tests or precipitation reactions, which can provide information about the presence of certain elements.

5. What challenges might arise when trying to find element X in an unknown compound?

One of the main challenges in finding element X in an unknown compound is the complexity and variety of chemical compounds. Different compounds may require different analytical techniques, and some compounds may contain elements in very small amounts or in complex arrangements, making them difficult to detect. Additionally, the presence of impurities or contaminants can also complicate the analysis process.

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