Moles and Avogadro’s Numbers

Iron provides only 0.5 mole while sulfur provides 0.625 mole. Iron is present in the smaller stoichiometric amount.

Twelve moles of water react with one mole Al₄C₃. Mass = 12 × 18 = 216 g.

Each mole KMnO₄ contains four moles oxygen atoms. Therefore, 0.25 mole contains one mole oxygen atoms.

One mole Pb(NO₃)₂ forms one mole PbO whose molar mass is 223 g.

1.6 g oxygen equals 0.05 mole. Therefore, the number of molecules equals 0.05 × Avogadro's number.

Twenty-five grams equal 0.25 mole CaCO₃. The same amount of CO₂ occupies 5.6 dm³ at STP.

Moles of CS₂ = 19/76 = 0.25 mol. According to the equation, 1 mol CS₂ produces 2 mol SO₂. Therefore, 0.25 mol CS₂ forms 0.5 mol SO₂. Mass = 0.5 × 64 = 32 g.

One formula unit produces 5 ions (2 Al³⁺ + 3 SO₄²⁻). Therefore, 0.1 mol gives 0.5 mol ions = 3.011 × 10²³ ions.

4.6 g Na = 0.2 mol. From the equation, 2 mol Na produce 1 mol H₂. Hence 0.2 mol Na produces 0.1 mol H₂.

Equal coefficients indicate equal numbers of moles.

Benzene contains six carbon atoms per molecule.

One mole methane requires two moles oxygen. Therefore, oxygen required is 64 g.

Twelve moles of water react with one mole Al₄C₃. Twelve × 18 = 216 g.

Molecular formula becomes C₆H₁₂O₆, containing twelve hydrogen atoms.

Gas volumes follow mole ratios. Hydrogen volume is three times nitrogen volume.

One mole pentane forms eleven moles of gaseous products. One-quarter mole forms 2.75 moles.

Nineteen grams correspond to 0.25 mole CS₂. This produces 0.5 mole SO₂ having a mass of 32 g.

One formula unit produces five ions. Therefore, 0.1 mole gives 0.5 mole of ions, equal to 3.011 × 10²³ ions.

4.6 g Na equals 0.2 mole. According to the equation, 2 moles Na produce 1 mole H₂. Thus, 0.2 mole Na produces 0.1 mole H₂.