The molecular weight of Propylene Glycol [CH₃CH(OH)CH₂OH] is 76.0949.

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: Propylene Glycol [CH₃CH(OH)CH₂OH] Molecular Weight Calculation

Step 1: Find out the chemical formula and determine constituent atoms and their number in a Propylene Glycol molecule.
From the chemical formula, you will know different atoms and their number in a Propylene Glycol molecule. Chemical formula of Propylene Glycol is C₃H₈O₂. From the chemical formula of Propylene Glycol, you can find that one molecule of Propylene Glycol has three Carbon (C) atoms, eight 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 Propylene Glycol molecule by multiplying its atomic weight by its number.

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

Number of Hydrogen atoms in Propylene Glycol: 8
Atomic weight of Hydrogen (H): 1.008
Total weight of Hydrogen atoms in Propylene Glycol: 1.008 x 8 = 8.064

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

Step 4: Calculate the molecular weight of Propylene Glycol by adding up the total weight of all atoms.

Molecular weight of Propylene Glycol: 36.0321 (Carbon) + 8.064 (Hydrogen) + 31.9988 (Oxygen) = 76.0949

So the molecular weight of Propylene Glycol is 76.0949.

Propylene Glycol [CH₃CH(OH)CH₂OH] 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