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

[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

please help me this and explain how did yo get it...

-westy
No Peace-out!

 

[Stevedye56]

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

 

[Blueshift5]

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.