Finding the formula of the metal

In summary, a question regarding the formula of a metal oxide with conflicting information caused confusion. The asker provided a potential solution, but the validity of the question itself was questioned. Ultimately, the formula X2O3 was determined, with the metal being Aluminium (Ar=27). However, the accuracy of the answer is uncertain due to contradictory information.
  • #1
299
20
Homework Statement
0.1 mol of metal X (Ar = 27) was burned in oxygen to give an oxide with mass of 5.1g. What is the formula of the metal oxide if it has a relative molecular mass of 30?

The choices are
XO
X2O3
XO2
X2O

The answer says X2O

But if I add up X2O the RMM is 70 not 30
Relevant Equations
This question is confusing
I don't understand how the RMM could be 30
I haven't gone into a solution cause I found this question confusing
 
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  • #2
Something is definitely wrong with the question and the answer given.

My bet is it should read: "0.1 mol of metal X (Ar = 27) was burned in oxygen to give an oxide with mass of 5.1g. What is the formula of the metal oxide?"
 
  • #3
I found the mass of the X by 27x0.1=2.7g
I subtracted 5.1g-2.7g=2.4g of oxygen
So changed the mass of oxygen to moles which = 0.15
Ratio it with 0.1 mol of X and I get 1:1.5
So X:O is 2:3 ratio
There for X2O3
Which makes sense cause At=27 is Aluminium
And Aluminium Oxide is Al2O3
 
  • #4
Your logic is good but it doesn’t apply to what is asked. The truly confusing part is the “(Ar=27)” and the 5.1 g. :)

If we ignore that part, the rest of the question tracks normally.

If RMM=30:

XO case: atomic mass X = 14 (N, nonmetal)
X2O3 case: atomic mass X= -9 (not real)
XO2 case: atomic mass X=-2 (not real)
X20 case: atomic mass X=7 (Li)
This should be the end of the problem.

balanced equation

2Li (.1 mol) + 1/2O2 ——-> Li2O (.05 mol)

It does make 1.5 g of product. A dyslexic 5.1 g?
 
Last edited:
  • #5
chemisttree said:
Your logic is good but it doesn’t apply to what is asked.

Let's not confuse the OP further. Question asks what is the formula and that's exactly what OP calculated, so their logic applies. Answer depends on which parts of the contradicting information given in the question one considers erroneous and decides to ignore.
 

1. What is the process for finding the formula of a metal?

The process for finding the formula of a metal involves conducting experiments and analyzing data to determine the chemical composition of the metal. This includes measuring the mass and volume of the metal, performing chemical reactions, and using various analytical techniques such as spectroscopy and chromatography.

2. What information is needed to find the formula of a metal?

To find the formula of a metal, you will need to know the mass and volume of the metal, as well as the results of any chemical reactions or analytical techniques performed on the metal. You may also need to know the atomic mass and valence of the metal, which can be found on the periodic table.

3. How do you determine the valence of a metal?

The valence of a metal can be determined by examining its electron configuration. The number of valence electrons, or electrons in the outermost energy level, corresponds to the metal's valence. For example, if a metal has 2 valence electrons, its valence would be 2.

4. Can the formula of a metal change?

Yes, the formula of a metal can change depending on the conditions it is exposed to. For example, if a metal is heated or reacts with another substance, it may form a different compound with a different formula. This is why it is important to specify the conditions under which the formula was determined.

5. Why is it important to find the formula of a metal?

Finding the formula of a metal is important for understanding its properties and behavior. The formula provides information about the chemical composition of the metal, which can help scientists predict how it will react with other substances and how it can be used in various applications.

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