Given
- Moles of ethane: 3 mol
- Formula of ethane: C₂H₆ (per molecule: 2 carbon atoms, 6 hydrogen atoms)
- Avogadro’s number: \( N_A \approx 6.022 \times 10^{23} \,\text{mol}^{-1} \)
(i) Number of moles of carbon atoms
- 1 mole of C₂H₆ contains 2 moles of C atoms.
- Therefore, 3 moles of C₂H₆ contain: \( 3 \times 2 = 6 \) moles of carbon atoms.
(i) Number of moles of carbon atoms = 6 mol.
(ii) Number of moles of hydrogen atoms
- 1 mole of C₂H₆ contains 6 moles of H atoms.
- Therefore, 3 moles of C₂H₆ contain: \( 3 \times 6 = 18 \) moles of hydrogen atoms.
(ii) Number of moles of hydrogen atoms = 18 mol.
(iii) Number of molecules of ethane
- 1 mole of any substance contains \( N_A \approx 6.022 \times 10^{23} \) molecules.
- Therefore, 3 moles of C₂H₆ contain: \( 3 \times 6.022 \times 10^{23} \approx 1.81 \times 10^{24} \) molecules.
(iii) Number of molecules of ethane ≈ \( 1.81 \times 10^{24} \).