Final answer:
To determine the grams of oxygen needed to react with 2.4g of magnesium, calculate the moles of magnesium and then use the stoichiometry of the reaction to find the moles of oxygen required. After converting moles of oxygen to grams, the nearest answer is 1.6g. Therefore, correct option is a.
Step-by-step explanation:
In the balanced chemical equation 2Mg + O₂ → 2MgO, it shows that 2 moles of magnesium will react with 1 mole of oxygen molecules to produce 2 moles of magnesium oxide. To find the grams of oxygen needed, we can first calculate the molar mass of oxygen which is 32 g/mole (16 g/mol x 2).
Given that you have 2.4 g of magnesium, you can use the molar ratio between magnesium and oxygen from the balanced equation to determine the amount of oxygen needed. From the equation, 2 moles of magnesium react with 1 mole of oxygen, so:
(2.4 g Mg) / (24.31 g/mol Mg) x (1 mol O₂) / (2 mol Mg)
= 0.0492 mol O₂
To find the grams of oxygen, we can multiply the number of moles by the molar mass of oxygen:
(0.0492 mol O₂) x (32 g/mol O₂) = 1.57 g O₂
Therefore, you would need approximately 1.6 grams of oxygen to react completely with 2.4 grams of magnesium.