The molecular weight of n-Butanol [CH₃(CH₂)₃OH] is 74.1222.

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: n-Butanol [CH₃(CH₂)₃OH] Molecular Weight Calculation

Step 1: Find out the chemical formula and determine constituent atoms and their number in a n-Butanol molecule.
From the chemical formula, you will know different atoms and their number in a n-Butanol molecule. Chemical formula of n-Butanol is C₄H₁₀O. From the chemical formula of n-Butanol, you can find that one molecule of n-Butanol has four Carbon (C) atoms, ten Hydrogen (H) atoms and one Oxygen (O) atom.

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 n-Butanol molecule by multiplying its atomic weight by its number.

Number of Carbon atoms in n-Butanol: 4
Atomic weight of Carbon: 12.0107
Total weight of Carbon atoms in n-Butanol: 12.0107 x 4 = 48.0428

Number of Hydrogen atoms in n-Butanol: 10
Atomic weight of Hydrogen: 1.008
Total weight of Hydrogen atoms in n-Butanol: 1.008 x 10 = 10.08

Number of Oxygen atoms in n-Butanol: 1
Atomic weight of Oxygen: 15.9994
Total weight of Oxygen atoms in n-Butanol: 15.9994 x 1 = 15.9994

Step 4: Calculate the molecular weight of n-Butanol by adding up the total weight of all atoms.

Molecular weight of n-Butanol: 48.0428 (Carbon) + 10.08 (Hydrogen) + 15.9994 (Oxygen) = 74.1222

So the molecular weight of n-Butanol is 74.1222.

n-Butanol [CH₃(CH₂)₃OH] 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:

• Deoxyn-Butanol (C5H10O4) Molecular Weight Calculation