Question

calculate the mass of magnesium oxide when 24g of magnesium reacts with 32g of Oxygen. Also find the weight of Oxygen left unused after the reaction.​

Answer 1

2Mg + O2 -----------------> 2MgO

From the reaction equation,

48 g Mg reacts with 32g O2 to give 80g MgO

24 g Mg reacts with 16g O2 to give 40g MgO

Hence, 24 g Mg gives 40g MgO

and mass of O2 left is 32-16=16g