Magnesium will combine with oxygen gas to form magnesium oxide according to the balanced equation below. \( 2 \mathrm{Mg}+\mathrm{O}_{2} \rightarrow 2 \mathrm{MgO} \) 85 grams of magnesium metal and 125 grams of oxygen gas are allowed to react. If the reaction runs to completion, which reactant will be depleted (limiting reagent) first? Oxygen Both will deplete at the same time. Magnesium More information is needed in order to answer the question.

To determine the limiting reagent, we first need to calculate the number of moles of each reactant. The molar mass of magnesium (Mg) is about 24.31 g/mol, so 85 grams of magnesium is approximately 3.5 moles. The molar mass of oxygen (O₂) is about 32 g/mol, so 125 grams of oxygen is about 3.9 moles. According to the balanced equation, we need 1 mole of O₂ for every 2 moles of Mg, which means we would need about 1.75 moles of O₂ to react with 3.5 moles of Mg. Since we have more than enough oxygen, magnesium will be the limiting reagent and will deplete first. This reaction is a classic in chemistry classrooms because it beautifully illustrates how stoichiometry works in real-world applications. Beyond the classroom, this type of reaction is essential in industrial settings, such as the production of magnesium oxide, which is used in refractory materials, electronics, and even as a food additive. Understanding the limiting reagent helps chemists optimize reactions in various manufacturing processes, resulting in both efficiency and cost-effectiveness!