Final answer:
To find the mass of oxygen that will react with 2.64 g of magnesium, calculate the number of moles of magnesium, use the stoichiometric ratio from the balanced chemical equation to find the moles of oxygen needed, and then convert this to mass.
Step-by-step explanation:
The mass of oxygen that will react with 2.64 g of magnesium can be determined by using stoichiometry based on the balanced chemical equation 2Mg (s) + O₂(g) → 2MgO (s). Firstly, you must calculate the moles of magnesium by dividing its mass by the molar mass of magnesium (24.305 g/mol). With this value, you can find the molar ratio of magnesium to oxygen from the balanced equation and calculate the moles of oxygen required to react with magnesium. Subsequently, multiplying the moles of oxygen by the molar mass of oxygen (32 g/mol for O₂) gives you the mass of oxygen that will react.