1. What is Exact Molecular Weight?

The exact molecular weight (MW) of a compound is the sum of the exact isotopic masses of its constituent atoms. Unlike average molecular weight, it accounts for the specific isotopes of each element present in the molecule.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• Each element's contribution is calculated based on its most abundant natural isotope
• The calculation accounts for the exact count of each atom in the molecule
• Results are given in unified atomic mass units (u)

3. Importance of Exact MW

Details: Exact molecular weight is crucial for mass spectrometry, high-resolution analytical chemistry, and precise stoichiometric calculations.

4. Using the Calculator

Tips: Enter the molecular formula using standard notation (e.g., C6H12O6 for glucose). The calculator will parse the formula and sum the exact isotopic masses.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between exact and average molecular weight?
A: Exact MW uses the most abundant isotope for each element, while average MW uses weighted averages of all natural isotopes.

Q2: How are molecular formulas parsed?
A: The calculator recognizes element symbols and subscripts (e.g., C6H12O6 is parsed as 6 carbons, 12 hydrogens, and 6 oxygens).

Q3: What elements are supported?
A: All common elements in the periodic table are supported with their most abundant natural isotopes.

Q4: How accurate are the results?
A: Results are accurate to 4 decimal places using the most recent IUPAC isotopic mass data.

Q5: Can I calculate MW for charged species?
A: For ions, you would need to account for the mass of electrons gained or lost (not currently implemented in this calculator).