Number of moles and formula units in 100g of KClO3 Calculate each of the following quantities
The correct answer and explanation is:
Correct Answer:
Number of moles: 0.815 mol
Number of formula units: 4.91 × 10²³ formula units
Explanation:
Potassium chlorate (KClO₃) is a chemical compound used in laboratories and industries as an oxidizing agent. To determine the number of moles in 100 grams of KClO₃, first calculate its molar mass. The atomic masses are: potassium (K) is about 39.10 g/mol, chlorine (Cl) is about 35.45 g/mol, and oxygen (O) is about 16.00 g/mol. Since there are three oxygen atoms in the formula, the total molar mass of oxygen in one formula unit is 3 × 16.00 = 48.00 g/mol. Adding these up gives the molar mass of KClO₃ as 39.10 + 35.45 + 48.00 = 122.55 g/mol.
Next, use the basic mole formula:
Number of moles = given mass (g) / molar mass (g/mol)
So, the number of moles in 100 g of KClO₃ is 100 g ÷ 122.55 g/mol = 0.815 mol.
To find the number of formula units, remember that one mole of any substance contains Avogadro’s number of particles, which is 6.022 × 10²³. Therefore, multiply the moles by Avogadro’s number:
Number of formula units = number of moles × Avogadro’s number
So, 0.815 mol × 6.022 × 10²³ = 4.91 × 10²³ formula units.
This calculation shows how mass, molar mass, and Avogadro’s number connect mass at the macroscopic scale with particles at the atomic level. This relationship allows chemists to determine how much of a substance is needed or produced in a reaction. Knowing moles and formula units is vital for stoichiometry, balancing equations, and preparing solutions in labs and industries. It bridges laboratory measurements and atomic-level understanding, forming the basis for predicting yields and understanding chemical reactions quantitatively.