Question

What is meant by the law of conservation of mass? If 12 g of C is burnt in the presence of O₂ , how much CO₂ will be formed? 

[Atomic mass of C = 12 u, O = 16 u]

Answer 1

Law of conservation of mass: This law states that “atoms are neither created nor destroyed in a chemical reaction”. 

This means that the total mass of the products formed in chemical reaction must be equal to the mass of reactants consumed. 

Carbon + oxygen → CO₂ 

Mass of carbon = 12g 

Mass of oxygen = 32g 

Mass of CO₂ =? 

According to the law of conservation of mass, 

Sum of masses of reactants = Sum of masses of of products 

Hence, 12g + 32g = 44g 

Thus, the amount of CO₂ formed is 44g.