Question

How many moles of magnesium are needed to react with 3.0 mol of O₂?

2Mg(s) + O₂(g) → 2MgO(s)

A) 1.0 mol

B) 1.5 mol

C) 2.0 mol

D) 3.0 mol

E) 6.0 mol

Answer 1

For the reaction of magnesium with oxygen to form magnesium oxide, the balanced equation shows a 2:1 mole ratio of magnesium to oxygen. Therefore, to react with 3.0 moles of O₂, 6.0 moles of magnesium are needed.

option d is the correct

Step-by-step explanation:

The question asks how many moles of magnesium are needed to react with 3.0 mol of O₂ gas according to the chemical equation:

2Mg(s) + O₂(g) → 2MgO(s)

According to the balanced chemical equation, two moles of magnesium react with one mole of oxygen to produce two moles of magnesium oxide (MgO). So, for every mole of O₂, you need two moles of Mg. Given that you have 3.0 moles of O₂, you'd need:

3.0 mol O₂ × (2 mol Mg / 1 mol O₂) = 6.0 mol Mg

This shows that for every mole of O₂, two moles of Mg are needed. Since we have 3.0 moles of O₂, we multiply by the ratio determined from the balanced equation to find out that we need 6.0 moles of Mg to react completely.