Moles and Avogadro’s Numbers

Multiplying the mass of one atom by Avogadro's number gives approximately 16 g mol⁻¹.

Every molecule contains four chlorine atoms. Therefore, 0.5 mole CCl₄ contains 2 moles of chlorine atoms.

One mole H₂S produces 1.5 moles sulfur. The mass becomes 1.5 × 32 = 48 g.

The sample contains 0.25 mole urea. With molar mass 60 g mol⁻¹, the mass equals 15 g.

Ten grams correspond to 0.1 mole CaCO₃, producing 0.1 mole CO₂ occupying 2.24 dm³ at STP.

One mole of phosphorus molecules requires five moles of oxygen. Therefore, 0.25 mole requires 1.25 moles.

OH⁻ contains eight electrons from oxygen, one from hydrogen, and one extra electron due to the negative charge.

The ratio of H₂O to CO₂ is 3:2. Therefore, 3 moles of CO₂ correspond to 4.5 moles of H₂O.

The atomic mass of helium is four grams per mole.

Number of moles is inversely proportional to molar mass.

Percentage yield = (0.45 ÷ 0.75) × 100 = 60%.

The balanced equation is 3Fe + 4H₂O → Fe₃O₄ + 4H₂. Their sum is 12.

Avogadro's law relates gas volume directly with the number of molecules at constant temperature and pressure.

The sample contains 0.25 mole of CO₂. Since one mole weighs 44 g, the mass is 11 g.

Half a mole of CO₂ occupies 11.2 dm³ at STP.

The molar mass divided by Avogadro's number gives the mass of one molecule.

Sixty-four grams of SO₂ equal one mole, producing one mole of SO₃.

One atomic mass unit is defined as one-twelfth the mass of a carbon-12 atom.

Actual yield equals 80% of theoretical yield. Therefore, 0.80 × 5 = 4 moles.