Question

0.5 get of magnesium is burnt with 0.25g (oxygen) in a closed vessel . Which reactant is left in excess and how much ? (At. wt. Mg = 24.3

Answer 1

Answer:

Magnesium is left by 0.12g

Explanation:

2Mg+O2=2MgO

moles of Mg= (0.5/24.3)=0.0206

moles of oxygen = (0.25/32)= 0.0078

For2 moles of magnesium= 1 mole of oxygen is required

1 mole of Mg= 0.5 mol of oxygen

0.0206 mol of Mg= 0.0103 mol of 0xygen is required but we have only 0.0078 mol of oxygen, so magnesium will be left

1 mol of oxygen requires 2 mol of Mg

So, 0.0078 mol of oxygen requires 0.0156 moles of magnesium

So, 0.005 mol of magnesium will be left which is 0.12g