# Help Westy Find Empirical & Molecular Formulas: K, Mn, O; Molar Mass 158/mol

• westside
In summary, empirical formulas show the simplest whole number ratio of elements in a compound, while molecular formulas show the actual number of each type of atom in a molecule. To determine the empirical formula, the mass of each element must be converted to moles and then divided by the smallest number to find the ratio. Molar mass is the mass of one mole of a substance and is calculated by adding the atomic masses of each element in the compound. The molecular formula can be found by dividing the given molar mass by the calculated molar mass of the empirical formula. The empirical and molecular formulas can be the same if the compound's molecular formula is the simplest possible ratio, but will be different if the molecular formula is a multiple of the empirical formula
westside
Kinda help me this..when I am in our class, our teacher discuss how to determine the empirical formula and the molecular formula of a compound having the given percentage composition and molar mass but i aint listen because i have headache.

a) 24.68% K, 34.81% Mn, and 40.51% O;molar mass=158/mol

and this please, finding the number of grams
1.)62x10to the power of23formula units of Ca (MnO4)2

-westy
No Peace-out!

At least show some attempt. You have to find the grams of each element. Start with that.

Dear Westy,

I understand that you may have missed your teacher's lesson on determining empirical and molecular formulas due to a headache, but I am happy to help you understand the process.

First, let's review the definitions of empirical and molecular formulas. The empirical formula is the simplest whole number ratio of elements present in a compound, while the molecular formula is the actual number of atoms of each element in a molecule.

To determine the empirical formula, we need to find the moles of each element present in the compound. We can do this by dividing the mass percentages by the molar mass of the compound and then converting to moles. For the compound given, we have:

K: (24.68/39.10) = 0.631 moles
Mn: (34.81/54.94) = 0.634 moles
O: (40.51/16.00) = 2.532 moles

Next, we need to find the smallest whole number ratio of these moles. In this case, we can divide all the moles by 0.631 to get a ratio of 1:1:4. This means that the empirical formula is KMnO4.

To find the molecular formula, we need to know the molar mass of the compound. Since the given molar mass is 158 g/mol, we can divide this by the molar mass of the empirical formula (158/158 = 1). This means that the molecular formula is the same as the empirical formula, KMnO4.

For the second question, we need to convert the given number of formula units (62 x 10^23) to moles. We can do this by multiplying by Avogadro's number (6.022 x 10^23). This gives us 3.733 x 10^25 moles of Ca(MnO4)2.

To find the number of grams, we can multiply the number of moles by the molar mass of the compound. The molar mass of Ca(MnO4)2 can be calculated by adding the molar masses of each element: Ca (40.08 g/mol) + 2 x Mn (54.94 g/mol) + 8 x O (16.00 g/mol) = 294.92 g/mol.

Therefore, the number of grams of Ca(MnO4)2 is (3.

## 1. What is the difference between empirical and molecular formulas?

Empirical formulas show the simplest whole number ratio of elements in a compound, while molecular formulas show the actual number of each type of atom in a molecule.

## 2. How do you determine the empirical formula from given elements and their masses?

To determine the empirical formula, you need to find the mass of each element in the compound and convert it to moles. Then, divide each element's moles by the smallest number to find the ratio. The resulting numbers will be the subscripts of the elements in the empirical formula.

## 3. What is the molar mass of a compound and how is it calculated?

Molar mass is the mass of one mole of a substance and is calculated by adding the atomic masses of each element in the compound. The units for molar mass are grams per mole (g/mol).

## 4. How can you find the molecular formula from the empirical formula and the molar mass?

To find the molecular formula, you need to know the empirical formula and the molar mass of the compound. First, calculate the molar mass of the empirical formula. Then, divide the given molar mass by the calculated molar mass of the empirical formula. The resulting number will be the ratio between the two, which can be used as the subscripts for the molecular formula.

## 5. Can the empirical and molecular formulas be the same?

Yes, if the compound's molecular formula is the simplest possible ratio, then it will be the same as the empirical formula. However, if the compound's molecular formula is a multiple of the empirical formula, then they will be different.

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