Question

2g of magnesium is burnt in a close vessel containing 3g of oxygen
a. Which one is limiting reaction?
b. Calculate the mole of reactant left over
c. how many gram of mgo are produced.

Answer 1

Answer:

Balanced equation:

2Mg(s) + O2(g) → 2MgO(s)

2mol Mg react with 1 mol O2

Molar mass Mg = 24.3g/mol

Molar mass O = 16g/mol.

Molar mass O2 = 32g/mol

48.6g Mg react with 32g O2

Now you know that mass O2 is less than the mass of Mg

In the problem , you have excess O2 = Mg is limiting

But let us calculate actual mass of O2 reacted

2g Mg react with ; 2g Mg * 32gO2/ 48.6g Mg = 1.32g O2

Once again showing that Mg is limiting.