For the following question(s),consider the following equation.
2Mg + O 2 → 2MgO
-The number of moles of oxygen gas needed to react with 4.0 moles of Mg is ________.

Question

Quizplus · Accepted Answer

According to the balanced chemical equation, 2 moles of Mg react with 1 mole of O2. Therefore, to react with 4 moles of Mg, we need 2 x 4 = 8 moles of O2. However, the equation only has 1 mole of O2 on the reactant side, so we need to double it to get 2 moles of O2. Therefore, the number of moles of O2 needed is 2. The answer is choice B.

For the Following Question(s),consider the Following Equation