Answer:
- 7.04 × 10²⁴ molecules of Na₂O
Explanation:
1) Balanced chemical equation (given):
- 4 Na(s) + O₂ (g) → 2Na₂O (s)
2) Mole ratio:
3) Number of moles of O₂ in 187 grams of oxygen:
- Molar mass O₂ = 32.00 g/mol
- Number of moles = mass in grams / molar mass = 187 g / 32.00 g/mol = 5.844 mol
4) Number of moles of Na₂O:
- Proportion: 1 mol O₂ / 2 mol Na₂O = 5.844 mol O₂ / x
- x = 5.844 mol O₂ (2 mol Na₂O / 1 mol O₂) = 11.688 mol Na₂O
5) Number of molecules
- Number of molecules = number of moles × Avogadro's number
- Number of molecules = 11.688 mol × 6.022 × 10²³ molecules/mol =
= 7.04 × 10 ²⁴ molecules ← answer
The answer is rounded to three significant figures.
