What is the molar mass of Na_2SO_4?

• A. 125.98 amu
• B. 174.12 amu
• C. 142.05 amu
• D. 119.06 amu

Answer: (C)

Verified step by step guidance

1. Identify the chemical formula of the compound: Na_2SO_4, which contains 2 sodium (Na) atoms, 1 sulfur (S) atom, and 4 oxygen (O) atoms.
2. Find the atomic masses of each element from the periodic table: sodium (Na) ≈ 22.99 amu, sulfur (S) ≈ 32.07 amu, and oxygen (O) ≈ 16.00 amu.
3. Calculate the total mass contributed by each element by multiplying the atomic mass by the number of atoms in the formula: for sodium, multiply 22.99 amu by 2; for sulfur, multiply 32.07 amu by 1; for oxygen, multiply 16.00 amu by 4.
4. Add all these contributions together to find the molar mass of Na_2SO_4 using the formula: \(\text{Molar mass} = 2 \times M_{Na} + 1 \times M_{S} + 4 \times M_{O}\).
5. Sum the values obtained to get the total molar mass of sodium sulfate (Na_2SO_4).