The molecular mass of sugar is found by adding the atomic masses of all the atoms in its chemical formula.
Here's a breakdown of how to calculate the molecular mass, using common table sugar (sucrose) as an example:
1. Understand the Chemical Formula
Sucrose's chemical formula is C₁₂H₂₂O₁₁. This tells us that one molecule of sucrose contains:
- 12 carbon (C) atoms
- 22 hydrogen (H) atoms
- 11 oxygen (O) atoms
2. Find the Atomic Masses
You'll need a periodic table to find the atomic masses of each element. The atomic masses are typically listed below the element symbol. We'll use the following approximate values:
- Carbon (C): 12 atomic mass units (amu)
- Hydrogen (H): 1 amu
- Oxygen (O): 16 amu
3. Calculate the Molecular Mass
Multiply the number of atoms of each element by its atomic mass, and then add the results together:
(12 × Atomic mass of C) + (22 × Atomic mass of H) + (11 × Atomic mass of O) = Molecular Mass of Sucrose
(12 × 12 amu) + (22 × 1 amu) + (11 × 16 amu) = Molecular Mass of Sucrose
144 amu + 22 amu + 176 amu = Molecular Mass of Sucrose
342 amu = Molecular Mass of Sucrose
Therefore, the molecular mass of sucrose (C₁₂H₂₂O₁₁) is approximately 342 atomic mass units (amu). You can also express this as 342 Daltons (Da) or grams per mole (g/mol).
In summary, to find the molecular mass of any sugar (or any molecule):
- Identify the chemical formula.
- Find the atomic masses of each element in the formula.
- Multiply the number of atoms of each element by its atomic mass.
- Add the results together.
