Question

1 g of Mg is burnt in closed vessel which contain 0.5 g of O2 a. which reactant is left in excess ? b. Find mass of excess reactant ?

Answer 1

2 Mg + O2 = 2MgO

48.64 g Mg consume 32 g of Oxygen

1 g of Mg will consume 32/48.64 = 0.658 g oxygen
but we have only 0.5 g oxygen. Therefore the excess reagent is mg.

0.5 g of oxygen need 0.5 x 48.64 / 32 g of Mg = 0.76g
Remaining Mg = 1-0.76 = 0.24 g