1. What is Accurate Mass?

Accurate mass refers to the calculated mass of a molecule based on the exact masses of its constituent isotopes. It differs from nominal mass which uses integer mass numbers. Accurate mass is crucial in mass spectrometry for identifying molecular formulas.

2. How Does the Calculator Work?

The calculator uses the accurate mass equation:

Where:

• \( AM \) — Accurate mass (u)
• \( A_i \) — Number of atoms (dimensionless)
• \( M_i \) — Atomic mass (u)

Explanation: The calculator sums the products of each atom count multiplied by its exact isotopic mass.

3. Importance of Accurate Mass

Details: Accurate mass measurement is essential for determining elemental composition, identifying unknown compounds, and distinguishing between isobaric species in mass spectrometry.

4. Using the Calculator

Tips: Enter the number of atoms for each element in your molecule. The calculator uses the most abundant natural isotopes for each element.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between accurate mass and exact mass?
A: Accurate mass refers to measured mass (experimental), while exact mass refers to calculated mass (theoretical). This calculator provides exact mass.

Q2: Why are the atomic masses not whole numbers?
A: The calculator uses isotopic masses which account for nuclear binding energy and thus differ slightly from the mass number.

Q3: How precise is this calculator?
A: The calculator provides mass to 6 decimal places using standard isotopic masses. For ultra-high precision work, consult more precise values.

Q4: Can I add other elements to this calculator?
A: This version includes C, H, N, O, S. Future versions may include more elements.

Q5: What's the typical accuracy needed for formula determination?
A: Typically ±5 ppm or better is needed for unambiguous formula determination in high-resolution mass spectrometry.