To calculate the number of oxygen atoms in 0.4 moles of KNO3 (potassium nitrate), you need to consider the molar ratio of oxygen atoms to the entire compound. Here's the step-by-step process:
Determine the chemical formula of the compound: The chemical formula of potassium nitrate is KNO3.
Identify the molar mass of KNO3: Find the molar mass of potassium nitrate by summing up the atomic masses of its constituent atoms.
Atomic mass of potassium (K) = 39.0983 g/mol Atomic mass of nitrogen (N) = 14.0067 g/mol Atomic mass of oxygen (O) = 15.999 g/mol (multiply by 3 since there are three oxygen atoms in KNO3)
Molar mass of KNO3 = (1 * atomic mass of potassium) + (1 * atomic mass of nitrogen) + (3 * atomic mass of oxygen) = (1 * 39.0983 g/mol) + (1 * 14.0067 g/mol) + (3 * 15.999 g/mol) = 101.1032 g/mol
Therefore, the molar mass of KNO3 is 101.1032 g/mol.
Calculate the number of moles of KNO3: Use the given quantity of KNO3 and its molar mass to determine the number of moles.
Moles of KNO3 = Mass of KNO3 / Molar mass of KNO3 = 0.4 moles
Determine the number of moles of oxygen atoms: Since there are three oxygen atoms in one mole of KNO3, multiply the number of moles of KNO3 by the molar ratio of oxygen atoms.
Moles of oxygen atoms = Moles of KNO3 * (3 moles of oxygen atoms / 1 mole of KNO3) = 0.4 moles * 3 = 1.2 moles
Convert moles to number of atoms: To convert moles of oxygen atoms to the number of atoms, use Avogadro's number, which states that there are 6.022 x 10^23 atoms in one mole of any substance.
Number of oxygen atoms = Moles of oxygen atoms * Avogadro's number = 1.2 moles * (6.022 x 10^23 atoms/mole) = 7.2264 x 10^23 atoms
Therefore, there are approximately 7.2264 x 10^23 oxygen atoms in 0.4 moles of KNO3.