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Question
Write the name of the following compound and deduce its molecular mass.
Na2SO4
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Solution
Na2SO4 - Sodium sulphate
| Molecule | Constituent elements | Atomic mass u | Number of atoms in the molecule | Atomic mass × number of atoms | Mass of the Constituents u |
| Na2SO4 | Na | 23 | 2 | 23 × 2 | 46 |
| S | 32 | 1 | 32 × 1 | 32 | |
| O | 16 | 4 | 16 × 4 | 64 |
The molecular mass of Na2SO4 = Sum of Constituent atomic masses
(Molecular mass of Na2SO4) = (Atomic mass of Na) × 2 + (Atomic mass of S) × 1 + (Atomic mass of O) × 4
= 2 × 23 + 1 × 32 + 4 × 16
= 46 + 32 + 64
= 142 u
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