High School

Sulphuric acid (H₂SO₄) has a molar mass of 98.1 g/mol. How many oxygen atoms are found in 75.0 g of H₂SO₄?

Answer :

Final answer:

To find the number of oxygen atoms in 75.0 g of H₂SO₄, calculate the moles from the given mass, then multiply by Avogadro's number and by four (since each H₂SO₄ molecule contains four oxygen atoms). Approximately 1.84 × 10²³ oxygen atoms are found in 75.0 g of sulfuric acid.

Explanation:

To determine how many oxygen atoms are in 75.0 g of sulfuric acid (H₂SO₄), we will first find out how many moles of H₂SO₄ are in 75.0 g and then calculate the number of oxygen atoms from there.

  1. Calculate the number of moles of H₂SO₄ using its molar mass.

    Moles of H₂SO₄ = mass (g) / molar mass (g/mol) = 75.0 g / 98.1 g/mol

  2. Multiply the number of moles of H₂SO₄ by Avogadro's number (6.022 × 10²³) to get the number of molecules.

    Number of molecules = moles of H₂SO₄ × Avogadro's number

  3. Since each molecule of H₂SO₄ contains four oxygen atoms, multiply the number of molecules by four to get the total number of oxygen atoms.

Completing the calculations:

  1. Moles of H₂SO₄ = 75.0 g / 98.1 g/mol = 0.7645 mol

  2. Number of molecules = 0.7645 mol × 6.022 × 10²³ molecules/mol = 4.60 × 10²² molecules

  3. Number of oxygen atoms = 4.60 × 10²² molecules × 4 atoms/molecule = 1.84 × 10²³ atoms

Therefore, there are approximately 1.84 × 10²³ oxygen atoms in 75.0 g of sulfuric acid.