The molecular weight of Methionine [C₅H₁₁NO₂S] is 149.21304.

Methionine (C₅H₁₁NO₂S) is an organic compound of five elements: Carbon, Hydrogen, Nitrogen, Oxygen, and Sulfur. The molecular weight of Methionine is 149.21304 which can be calculated by adding up the total weight (atomic weight multiplied by their number) of all its elements.

CALCULATION PROCEDURE: Methionine  [C₅H₁₁NO₂S] Molecular Weight Calculation

Step 1: Find out the chemical formula and determine constituent atoms and their number in a Methionine molecule.
From the chemical formula, you will know different atoms and their number in a Methionine molecule. The chemical formula of Methionine is C₅H₁₁NO₂S. From the chemical formula of Methionine, you can find that one molecule of Methionine consists of five Carbon (C) atoms, eleven Hydrogen (H) atoms, one Nitrogen (N) atom, two Oxygen atoms, and one Sulfur atom.

Step 2: Find out the atomic weights of each atom (from the 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 Nitrogen (N): 14.00674 (Ref: Jlab-ele007)
Atomic weight of Oxygen (O): 15.9994 (Ref: Jlab-ele008)
Atomic weight of Sulfur (S): 32.066 (Ref: Jlab-ele016)

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

Number of Carbon atoms in Methionine: 5
Atomic weight of Carbon (C): 12.0107
Total weight of Carbon atoms in Methionine: 12.0107 x 5 = 60.0535

Number of Hydrogen atoms in Methionine: 11
Atomic weight of Hydrogen (H): 1.008
Total weight of Hydrogen atoms in Methionine: 1.008 x 11 = 11.088

Number of Nitrogen atoms in Methionine: 1
Atomic weight of Nitrogen (N): 14.00674
Total weight of Nitrogen atoms in Methionine: 14.00674 x 1 = 14.00674

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

Number of Sulfur atoms in Methionine: 1
Atomic weight of Sulfur (S): 32.066
Total weight of Sulfur atoms in Methionine: 32.066 x 1 = 32.066

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

Molecular weight of Methionine: 60.0535 (Carbon) + 11.088 (Hydrogen) + 14.00674 (Nitrogen) + 31.9988 (Oxygen) + 32.066 (Sulfur) = 149.21304

So the molecular weight of Methionine is 149.21304.

Methionine [C₅H₁₁NO₂S] Molecular Weight Calculation

REFERENCES:

• Lanl-1: https://periodic.lanl.gov/1.shtml 
• Jlab-ele006: https://education.jlab.org/itselemental/ele006.html 
• Jlab-ele007: https://education.jlab.org/itselemental/ele007.html
• Jlab-ele008: https://education.jlab.org/itselemental/ele008.html
  
• Jlab-ele016: https://education.jlab.org/itselemental/ele016.html

See also:

• Hydrogen chloride molecular weight calculation