1. Explain the difference between molecular formulas and empirical formulas. Giv

Question

1. Explain the difference between molecular formulas and empirical formulas. Give an example of a substance whose empirical formula is different from its molecular formula. Give an example of a substance whose empirical formula and molecular formula are the same.

2. A sample of an ionic compound that is often used as a dough conditioner is analyzed and found to contain 4.650 g of potassium, 9.502 g of bromine, and 5.708 g of oxygen.
What is the empirical formula for this compound?

3. A sample of an ionic compound that is used in the semiconductor industry is analyzed and found to contain 59.739 g of indium and 99.583 g of tellurium.
What is the empirical formula for this compound?

4. An ionic compound sometimes called TKPP is used as a soap and detergent builder. It is 47.343% potassium, 18.753% phosphorus, and 33.904% oxygen.
What is the empirical formula for this compound

5.

Explanation / Answer

Empirical formula represents the simplest atomic ratio between the elements in the compound. It may or may not be same as molecular formula.

Molecular formula represents the actual numbers of atoms of each element that occur in single stablemolecule of the compound.

Ex:1.diNitrogen tetraoxide has molecular formula N2O4

It's empirical formula is NO2

2.The molecular and empirical formula for carbon dioxide is CO2.

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2.Number of moles of potassium ,n1= mass / molar mass

n1= 4.650 g/ 39(g/ mol)

= 0.12 mol

Number of moles of bromine,n2= 9.502 g/(80(g/ mol)= 0.12 mol

Number of moles of oxygen,n3= 5.708g/(16(g/ mol)= 0.36 mol

n1:n2:n3= 0.12 : 0.12 : 0.36= 1:1:3

So empirical formula is KBrO3

3.number of moles ,n mass/ molar mass

n indium= 59.739 g/(115(g/mol))= 0.52 mol

n tellurium= 99.583 g/(127.6(g/ mol))= 0.78 mol

Empirical formula is the ratio of indiui: tellurium= 0.52 : 0.78= 1:1.5= 3:2

In3Te2

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