Question

(a) What is the law of conservation of mass?
(b) Calculate the molecular mass of calcium carbonate. (Atomic mass of Ca = 40 u, C = 12 u, and O= 16 u)
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Answer 1

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(a) The law of conservation of mass states that mass can be neither created nor destroyed during a chemical reaction. It means that the total mass of the reactants and the products involved in a reaction remains the same. 

(b) The molecular mass of a substance is the sum of the atomic masses of all the atoms present in 1 molecule of that substance.

The chemical formula of calcium carbonate is CaCO3

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Atomic mass of Ca = 40 u

Atomic mass of C = 12 u

Atomic mass of O = 16 u

∴Molecular mass of CaCO3 = [(1 × 40) + (1 × 12) + (3 × 16)] u = 100 u

Thus, the molecular mass of CaCO3 is 100 u.

Answer 2

(a) The law of conservation of mass states that mass can be neither created nor destroyed during a chemical reaction. It means that the total mass of the reactants and the products involved in a reaction remains the same. 

(b) The molecular mass of a substance is the sum of the atomic masses of all the atoms present in 1 molecule of that substance.

The chemical formula of calcium carbonate is CaCO3

Atomic mass of Ca = 40 u

Atomic mass of C = 12 u

Atomic mass of O = 16 u

∴Molecular mass of CaCO3 = [(1 × 40) + (1 × 12) + (3 × 16)] u = 100 u

Thus, the molecular mass of CaCO3 is 100 u.