Final answer:
To find the number of O2 molecules needed to react with 8.79 g of S, one should use stoichiometry and convert grams of S to moles, then use the balanced chemical equation to find the moles of O2 required, and finally convert this to molecules using Avogadro's number.
Step-by-step explanation:
The number of O2 molecules needed to react with 8.79 grams of sulfur (S) can be calculated using stoichiometry. To determine the amount of O2 required, we need the balanced chemical equation for the reaction of sulfur with oxygen, which is typically:
S(s) + O2(g) → SO2(g)
As per the equation, one mole of sulfur reacts with one mole of oxygen to produce sulfur dioxide. First, convert the mass of sulfur to moles by using its molar mass (approximately 32.07 g/mol). Then it's a straightforward mole-to-mole conversion to find the moles of O2, and with Avogadro's number (6.022 × 10²³ molecules/mol), you can convert the moles of oxygen to molecules.