1. What is Relative Formula Mass?

Relative Formula Mass (RFM) is the sum of the atomic masses of all atoms in a chemical formula. It's used to calculate the mass of a molecule or formula unit in atomic mass units (u).

2. How Does the Calculator Work?

The calculator uses the RFM equation:

Where:

• \( atomic\_masses \) — Array of atomic masses in atomic mass units (u)
• \( counts \) — Array of atom counts (integers)

Explanation: The equation multiplies each atomic mass by its count in the formula and sums all these products.

3. Importance of RFM Calculation

Details: RFM is fundamental in stoichiometry for converting between mass and moles of substances, essential for chemical calculations and laboratory work.

4. Using the Calculator

Tips: Enter atomic masses and counts as comma-separated or line-separated values. Both lists must have the same number of elements.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between RFM and molecular mass?
A: RFM is used for ionic compounds (formula units) while molecular mass is used for covalent molecules. The calculation method is identical.

Q2: What units are used for atomic masses?
A: Atomic mass units (u), where 1 u is 1/12 the mass of a carbon-12 atom.

Q3: How accurate should atomic masses be?
A: For most calculations, using values to 1 decimal place is sufficient. For precise work, use more decimal places.

Q4: Can I calculate RFM for hydrates?
A: Yes, include water molecules in your atomic masses and counts (H₂O would be 2 H and 1 O atoms).

Q5: What if my formula has parentheses?
A: Multiply each atom inside the parentheses by the subscript outside before entering values.