Solved Examples on Molar Mass
Example 1: Find the molar mass of Sodium Carbonate(Na2CO3).
Solution:
The chemical formula of Sodium Carbonate is Na2CO3. It contains two sodium atoms, one carbon atom and three oxygen atoms. We know that the molecular weight of Sodium (Na) is 22.98g/mol, Carbon (C) is 12.011 g/mol and Oxygen (O) is 16 g/mol. Therefore, the molar mass of sodium carbonate is
- Na = 2 × 22.98 = 45.96 g/mol
- C = 1 × 12.011 = 12.011 g/mol
- O = 3 × 16 = 48 g/mol
Molecular Weight of Na2CO3 = 45.96 + 12.011 + 48
= 105.971 amuTherefore, the molar mass of Na2CO3 is 105.971 g/mol.
Example 2: Find the molar mass of hydrochloric Acid (HCl).
Solution:
The chemical formula of Hydrochloric acid is HCl. It contains one Hydrogen atom, one chlorine atom. We know that the molecular weight of Hydrogen (H) is 1.0078g/mol, Chlorine (Cl) is 35.453 g/mol. Therefore, the molar mass of hydrochloric acid is
- H = 1 × 1.0078 = 1.0078 g/mol
- Cl = 1 × 35.453 = 35.453g/mol
Molecular Weight of HCl = 1.0078 + 35.543
= 36.460 g/molTherefore, the molar mass of HCl is 36.460 g/mol.
Example 3: Find the molar mass of Glucose (C6H11O6).
Solution:
The chemical formula of Glucose is C6H11O6. It contains six carbon atoms, eleven hydrogen atoms and six oxygen atoms. We know that the molecular weight of Carbon (C) is 12.011 g/mol, Hydrogen (H) is 1.0078 g/mol and Oxygen (O) is 16 g/mol. Therefore, the molar mass of glucose is,
- C = 6 × 12.011 = 72.066 g/mol.
- H = 12 × 1.0078 = 12.094 g/mol.
- O = 6 × 16 = 96 g/mol.
Molecular Weight of C6H11O6 = 72.066 + 12.094 + 96
= 180.16 g/mol.Therefore, the molar mass of Glucose is 180.16 g/mol.
Molar Mass
Molar Mass is defined as the mass in grams of one mole of the given compound. It is also called Molecular Weight.
Let’s learn about molar mass in more detail.