1. 21 g O₂
* Step 1: Convert grams to moles.
- The molar mass of O₂ is 32 g/mol (16 g/mol for each oxygen atom).
- Moles of O₂ = (21 g) / (32 g/mol) = 0.656 moles O₂
* Step 2: Calculate the number of oxygen atoms.
- 1 mole of O₂ contains 2 moles of oxygen atoms (because the formula is O₂).
- Atoms of oxygen = (0.656 moles O₂) * (2 moles O / 1 mole O₂) * (6.022 x 10²³ atoms/mol)
- Atoms of oxygen ≈ 7.91 x 10²³ atoms
2. 0.812 moles MgO
* Step 1: Determine the moles of oxygen atoms.
- The formula MgO indicates that there is 1 mole of oxygen atoms for every mole of MgO.
- Moles of oxygen atoms = 0.812 moles MgO * (1 mole O / 1 mole MgO) = 0.812 moles O
* Step 2: Calculate the number of oxygen atoms.
- Atoms of oxygen = (0.812 moles O) * (6.022 x 10²³ atoms/mol)
- Atoms of oxygen ≈ 4.89 x 10²³ atoms
3. 3.2 x 10²² molecules C₆H₁₂O₆
* Step 1: Determine the number of oxygen atoms per molecule.
- The formula C₆H₁₂O₆ indicates that there are 6 oxygen atoms in each molecule.
* Step 2: Calculate the total number of oxygen atoms.
- Atoms of oxygen = (3.2 x 10²² molecules) * (6 atoms O / 1 molecule)
- Atoms of oxygen = 1.92 x 10²³ atoms
