What is Molar Mass and Why Should You Care?
Molar mass is the mass of a given substance divided by its amount in moles. It's expressed in grams per mole (g/mol) and is fundamental to chemistry calculations.
Understanding molar mass allows you to convert between mass and moles, making it essential for stoichiometry, solution preparation, and chemical analysis.
How to Calculate Molar Mass
The formula for molar mass is:
[\text{Molar Mass} = \frac{\text{Mass of Substance (g)}}{\text{Number of Moles}}]
Where:
- Molar Mass is expressed in g/mol
- Mass of Substance is the weight in grams
- Number of Moles is the amount of substance
Calculation Example
For 150 grams of a substance containing 30 moles:
[\text{Molar Mass} = \frac{150 \text{ g}}{30 \text{ mol}} = 5.00 \text{ g/mol}]
The molar mass is 5.00 g/mol.
Common Molar Masses
| Substance | Molar Mass (g/mol) |
|---|---|
| Hydrogen (H₂) | 2.016 |
| Water (H₂O) | 18.015 |
| Carbon Dioxide (CO₂) | 44.01 |
| Sodium Chloride (NaCl) | 58.44 |
| Glucose (C₆H₁₂O₆) | 180.16 |
Related Calculations
To find moles from mass:
[\text{Moles} = \frac{\text{Mass}}{\text{Molar Mass}}]
To find mass from moles:
[\text{Mass} = \text{Moles} \times \text{Molar Mass}]