Question

Q3. Consider the reaction; Mg + O2 → MgO Calculate the mass of magnesium oxide possible if 2.5 g Mg reacts with 3.0 g O2? *

Answer 1

Answer:

mass of  magnesium oxide is 4.2 grams.

Explanation:

                     Balanced equation:  2Mg + O2 → 2MgO.

Given that 2.5 g Mg reacts with 3.0 g O2

• mass = moles * Mr
• moles = mass/Mr
• Mr = mass/moles

First find the moles of Mg:

moles = mass/Mr

moles = 2.5/ 24

moles = 0.104 moles

Using molar ratio, magnesium oxide will have same moles as Mg as they both have "2" molar ratio. So moles of Mg is 0.104 moles.

mass = moles * Mr

mass = 0.104 * 40

mass - 4.1667 g

mass = 4.2 g ___________this is the mass of MgO