Question

1. 2Mg + O₂ → 2MgO How many moles of MgO form if 6mol of oxygen react? *

2. 2Mg + O₂ → 2MgO How many moles of oxygen are required to react with 3.6mol of magnesium?
3. 2Mg + O₂ → 2MgO How many moles of magnesium are required to produce 5.5mol of MgO?

Answer 1

12 moles of MgO

1.8 moles of O₂

5.5 moles of Mg

Step-by-step explanation:

These questions are all related and they involve comparing the number of moles of reactant to products.

Here we use molar relationship because they express what happens in a reaction much more better.

Problem 1:

2Mg + O₂ → 2MgO

We work from the known to the unknown;

The known is oxygen gas; which is 6moles

Unknown is MgO;

1 mole of O₂ produced 2 mole of MgO

6 moles of O₂ will produce (6 x 2) moles of MgO

= 12 moles of MgO

Problem 2:

2Mg + O₂ → 2MgO

Known; 3.6 moles of Magnesium

Unknown; number of moles of oxygen;

2 moles of Mg reacted with 1 mole of O₂

3.6 moles of Mg will react with
`(3.6)/(2)` = 1.8 moles of O₂

Problem 3:

2Mg + O₂ → 2MgO

Known: number of of moles of MgO = 5.5moles

Unknown: number of moles of Mg = ?

2 moles of MgO will be produced from 2 moles of Mg

5.5 moles of MgO will be produced from
`(5.5 x 2)/(2)` = 5.5 moles of Mg