1. What is Molar Mass?

Molar mass is the mass of one mole of a substance (chemical element or chemical compound). It is a physical property defined as the mass of a given substance divided by the amount of substance in moles.

2. How to Calculate Molar Mass of Na₂S

The molar mass of sodium sulfide (Na₂S) is calculated by summing the atomic masses of its constituent atoms:

Where:

• Atomic Mass (Na) — 22.9898 g/mol (standard atomic weight of sodium)
• Atomic Mass (S) — 32.065 g/mol (standard atomic weight of sulfur)

Example Calculation: Using standard atomic weights: 2 × 22.9898 + 32.065 = 78.0446 g/mol

3. Importance of Molar Mass Calculation

Details: Molar mass is essential for converting between grams and moles of a substance, which is fundamental in stoichiometric calculations for chemical reactions and solution preparations.

4. Using the Calculator

Tips: Enter the atomic masses of sodium and sulfur. Default values are provided based on standard atomic weights. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: Why calculate molar mass?
A: Molar mass is needed for stoichiometric calculations, preparing solutions with specific concentrations, and determining molecular formulas from experimental data.

Q2: What's the difference between molecular weight and molar mass?
A: Molecular weight is the mass of one molecule (in atomic mass units), while molar mass is the mass of one mole of molecules (in grams per mole).

Q3: How precise are the standard atomic weights?
A: Standard atomic weights are based on the isotopic composition of elements found in normal terrestrial samples. For most calculations, they provide sufficient precision.

Q4: Does molar mass change with temperature?
A: No, molar mass is an intrinsic property that doesn't depend on temperature or pressure.

Q5: How is molar mass used in solution preparation?
A: To prepare a 1M solution, you dissolve the molar mass (in grams) of a substance in enough solvent to make 1 liter of solution.