1. What is Exact Mass?

Exact mass is the calculated mass of an ion or molecule based on the most abundant isotopes of each element. It provides high resolution mass spectrometry data that is crucial for molecular identification and characterization.

2. How Does the Calculator Work?

The calculator uses the exact mass formula:

Where:

• Atomic Masses — Precise isotopic masses in Daltons (Da)
• Counts — Number of atoms of each isotope (integer)

Explanation: The equation multiplies the atomic mass of each isotope by the number of atoms present and sums these values to get the total exact mass.

3. Importance of Exact Mass Calculation

Details: Exact mass calculations are essential for mass spectrometry analysis, molecular formula determination, and distinguishing between compounds with similar nominal masses.

4. Using the Calculator

Tips: Enter the atomic mass in Daltons (Da) with high precision (6 decimal places) and the integer count of atoms. Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between exact mass and molecular weight?
A: Exact mass uses precise isotopic masses, while molecular weight uses average atomic masses weighted by natural abundance.

Q2: How precise should the atomic masses be?
A: For high resolution calculations, use isotopic masses with at least 6 decimal places.

Q3: Can this calculator handle multiple elements?
A: This basic version calculates for one isotope at a time. For full molecular calculations, sum the exact masses of all constituent atoms.

Q4: What are common applications of exact mass?
A: Mass spectrometry, proteomics, metabolomics, and elemental composition analysis.

Q5: Where can I find precise isotopic masses?
A: From IUPAC's Atomic Weights and Isotopic Compositions or NIST Atomic Spectra Database.