(a) What is meant by the 'molar mass' of a substance? State the unit in which molar mass is usually expressed.(b) Calculate the molar masses of the following substances. Write the results with proper units.(i) Ozone molecule, O₃(ii) Ethanoic acid, CH₃COOH

Academic Chemistry NCERT Class 9

(a) Molar mass of a substance is the mass in grams. It is numerically equivalent to the sum of atomic masses of individual atoms in the molecular formula of that substance.

The molar mass of a substance is usually expressed as grams/mole.

(b) To calculate-

(i) Molar mass of ozone (O₃)

Molar mass of ozone = 16 + 16 +16 = 48 g/mol

(ii) Molar mass of acetic acid (CH₃COOH)

Molar mass of acetic acid = (2 × 12) + (4 × 1) + (2 × 16) = 60 g/mol

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Updated on: 10-Oct-2022

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