The molecular weight of Propionic acid [CH₃CH₂CO₂H] is 74.0789.

To calculate molecular weight of any compound, the first step is to know the constituent atoms and their number in that particular compound. Then calculate the total weight of each atom by multiplying its atomic weight by its number. The sum of total weight of all constituent atoms will be the molecular weight of the compound. Note that the value of atomic weight may differ slightly from different sources.

CALCULATION PROCEDURE: Propionic acid [CH₃CH₂CO₂H] Molecular Weight Calculation

Step 1: Find out the chemical formula and determine constituent atoms and their number in a Propionic acid molecule.
From the chemical formula, you will know different atoms and their number in a Propionic acid molecule. Chemical formula of Propionic acid is C₃H₆O₂. From the chemical formula of Propionic acid, you can find that one molecule of Propionic acid has three Carbon (C) atoms, six Hydrogen (H) atoms and two Oxygen (O) atoms.

Step 2: Find out atomic weights of each atom (from periodic table).

Atomic weight of Carbon (C): 12.0107 (Ref: Jlab-ele006)
Atomic weight of Hydrogen (H) : 1.008 (Ref: Lanl-1)
Atomic weight of Oxygen (O) : 15.9994 (Ref: Jlab-ele008)

Step 3: Calculate the total weight of each atom present in a Propionic acid molecule by multiplying its atomic weight by its number.

Number of Carbon atoms in Propionic acid: 3
Atomic weight of Carbon (C): 12.0107
Total weight of Carbon atoms in Propionic acid: 12.0107 x 3 = 36.0321

Number of Hydrogen atoms in Propionic acid: 6
Atomic weight of Hydrogen (H): 1.008
Total weight of Hydrogen atoms in Propionic acid: 1.008 x 6 = 6.048

Number of Oxygen atoms in Propionic acid: 2
Atomic weight of Oxygen (O): 15.9994
Total weight of Oxygen atoms in Propionic acid: 15.9994 x 2 = 31.9988

Step 4: Calculate the molecular weight of Propionic acid by adding up the total weight of all atoms.

Molecular weight of Propionic acid: 36.0321 (Carbon) + 6.048 (Hydrogen) + 31.9988 (Oxygen) = 74.0789

So the molecular weight of Propionic acid is 74.0789.

Propionic acid [CH₃CH₂CO₂H] Molecular Weight Calculation

REFERENCES:

• Lanl-1: https://periodic.lanl.gov/1.shtml 
• Pubchem-Hydrogen : https://pubchem.ncbi.nlm.nih.gov/element/Hydrogen 
• Jlab-ele006; https://education.jlab.org/itselemental/ele006.html
• Pubchem-6: https://pubchem.ncbi.nlm.nih.gov/element/6
• Jlab-ele008: https://education.jlab.org/itselemental/ele008.html
• Pubchem-8: https://pubchem.ncbi.nlm.nih.gov/element/8

See also:

• Apiose (C5H10O5) Molecular Weight Calculation