what is the formula of unit mass?

The formula unit mass (or unit mass) is the sum of the atomic masses of all the atoms in one formula unit of a compound. This is especially useful for ionic compounds, which are composed of ions rather than individual molecules.

How to Calculate Formula Unit Mass

1. Identify the compound- Determine the chemical formula of the ionic compound. Example: NaCl for sodium chloride.
2. Find atomic masses- Look up the atomic mass of each element in the compound, usually in atomic mass units (amu or u).
3. Multiply by the number of atoms- For each element, multiply its atomic mass by the number of atoms of that element in the formula unit.
4. Sum the results- Add all the values from step 3 to get the total formula unit mass.

Example: Formula Unit Mass of Sodium Chloride (NaCl)

• Compound: NaCl
• Atomic Masses: Sodium (Na) = 23 u, Chlorine (Cl) = 35.5 u

Multiply:

• 1 × 23 u (for Na)
• 1 × 35.5 u (for Cl)

Sum: 23 u + 35.5 u = 58.5 u

Conclusion: The formula unit mass of NaCl is 58.5 amu.