What is the relative molecular mass of sodium sulphate? (The relative atomic masses of Na, S and O are 23u, 32u and 16u respectively)

To find the relative molecular mass of sodium sulfate (Na₂SO₄), we need to consider the contributions of each element in the compound based on their respective atomic masses. Sodium sulfate consists of two sodium (Na) atoms, one sulfur (S) atom, and four oxygen (O) atoms. Let's break this down step by step.

Calculating the Mass Contributions

First, we will calculate the total mass contributed by each type of atom in sodium sulfate:

• Sodium (Na): There are 2 sodium atoms. The relative atomic mass of sodium is 23u. Therefore, the total mass from sodium is:
• 2 × 23u = 46u
• Sulfur (S): There is 1 sulfur atom. The relative atomic mass of sulfur is 32u. Thus, the total mass from sulfur is:
• 1 × 32u = 32u
• Oxygen (O): There are 4 oxygen atoms. The relative atomic mass of oxygen is 16u. Hence, the total mass from oxygen is:
• 4 × 16u = 64u

Summing Up the Contributions

Now that we have the individual contributions, we can add them together to find the total relative molecular mass of sodium sulfate:

• Total mass = Mass from sodium + Mass from sulfur + Mass from oxygen
• Total mass = 46u + 32u + 64u
• Total mass = 142u

Final Result

Therefore, the relative molecular mass of sodium sulfate (Na₂SO₄) is 142u. This value is essential in various applications, including stoichiometry in chemical reactions, where knowing the molecular mass helps in calculating the amounts of reactants and products involved.