Molecular Mass Calculator

Molecular Mass Formula:

\[ MW = \sum(atomic\_masses \times counts) \]

Molecular Mass:

1. What is Molecular Mass?

Molecular mass (or molecular weight) is the sum of the atomic masses of all the atoms in a molecule. It's expressed in atomic mass units (u) or grams per mole (g/mol). Molecular mass is crucial for stoichiometric calculations in chemistry.

2. How to Calculate Molecular Mass

The molecular mass is calculated using the formula:

\[ MW = \sum(atomic\_masses \times counts) \]

Where:

\( MW \) — Molecular weight/mass (g/mol)
\( atomic\_masses \) — Atomic masses of each element (g/mol)
\( counts \) — Number of atoms of each element in the molecule

Example: For water (H₂O):

2 Hydrogen atoms: 2 × 1.008 g/mol = 2.016 g/mol
1 Oxygen atom: 1 × 15.999 g/mol = 15.999 g/mol
Total molecular mass = 2.016 + 15.999 = 18.015 g/mol

3. Importance of Molecular Mass

Details: Molecular mass is essential for:

Stoichiometric calculations in chemical reactions
Preparing solutions with specific molar concentrations
Determining empirical and molecular formulas
Gas law calculations
Pharmaceutical dosage calculations

4. Using the Calculator

Instructions:

Enter elements and their counts separated by commas
Format: "Element count, Element count" (e.g., "H 2, O 1" for water)
If count is 1, you can omit it (e.g., "H 2, O" is equivalent to H₂O)
Element symbols are case-sensitive (e.g., "Co" is cobalt, "CO" would be carbon and oxygen)

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between molecular mass and molar mass?
A: They are numerically identical but conceptually different. Molecular mass refers to a single molecule, while molar mass refers to one mole (6.022×10²³ molecules) of a substance.

Q2: How do I calculate molecular mass for ionic compounds?
A: For ionic compounds, we calculate formula mass (sum of atomic masses of all atoms in the formula unit) using the same method.

Q3: Why are atomic masses not whole numbers?
A: Atomic masses account for natural isotopic abundance. For example, chlorine has isotopes Cl-35 (75%) and Cl-37 (25%), resulting in an average atomic mass of ~35.45.

Q4: How accurate are these calculations?
A: The calculator uses standard atomic weights. For precise work, use isotope-specific masses and exact isotopic composition.

Q5: What if my element isn't in the database?
A: The calculator includes common elements. For less common elements, please consult a complete periodic table.