Respuesta :

The empirical formula is [tex]Fe_{3}O_{4}[/tex].

Explanation:

Empirical formula is the easiest way of represent a chemical compound with representing the ratio of each element present in the compound. For finding the empirical formula, first we have to know the molar mass present in the given percentage of elements.

As we know that the molar mass of iron is 55.8 g/mol and oxygen in 16 g/mol, then dividing the percentage of elements given with their respective molar mass will give us the moles present in this composition.So,

             [tex]\frac{72}{56}=1.29 \text { moles of } F e[/tex]

             [tex]\frac{27.6}{16}=1.725 \text { moles of } 0[/tex]

Now the least among the two is 1.29, so we have to divide the moles of Fe and O with this to determine the ratio of each element. So, we are getting the ratio of 1:1.3, then if we multiply it by 3, we can get integer terms as 3:4. Thus, we obtained that Fe is 3 and O is  4. So the empirical formula will be [tex]Fe_{3}O_{4}[/tex].

Histrionicus

A compound is composed of 72% iron and 27.6% oxygen, the empirical formula is - [tex]Fe_3O_4[/tex]

we need to convert the given percent composition to grams, then convert the grams to moles by using the molar masses of the elements.

  • pick a 100-g sample of this unknown compound.
  • According to the given percent composition, this sample will contain

72% = Fe = 72 g

27.6% = O = 27.6 g

  • Now, use the molar masses of the two elements to determine the number of moles of each you have in this sample.

For Fe =[tex]\frac{ 72 \times 1\ mole\ of\ Fe}{55.84}[/tex] = 1.534 moles Fe

for O = [tex]\frac{27.6 \times 1\ mole\ of\ O}{16}[/tex] = 2.045 moles O

  • To get the mole ratio that exists between the elements in the compound, divide all values by the smallest one. This will get you
  • To do that, divide both values by the smallest one:

For Fe: [tex]\frac{1.534}{1.534}[/tex] = 1

For O: [tex]\frac{2.045}{1.534}[/tex] = 1.33

To get the smallest whole number ratio that exists between the two elements, multiply both values by  3 . This will help you get rid of the decimal fraction for oxygen.  

The empirical formula of the iron oxide will thus be

=

Thus, A compound is composed of 72% iron and 27.6% oxygen, the empirical formula is - [tex]Fe_3O_4[/tex]

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