The molecular weight of HEPES [4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid] [C₈H₁₈N₂O₄S] is 238.30668.

HEPES (C₈H₁₈N₂O₄S) is an organic compound of five elements: Carbon, Hydrogen, Nitrogen, Oxygen, and Sulfur. The molecular weight of HEPES is 238.30668 which can be calculated by adding up the total weight (atomic weight multiplied by their number) of all its elements.

CALCULATION PROCEDURE: HEPES [4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid]  [C₈H₁₈N₂O₄S] Molecular Weight Calculation

Step 1: Find the chemical formula and determine constituent atoms and their number in a HEPES molecule.
You will know different atoms and their number in a HEPES molecule from the chemical formula. The chemical formula of HEPES [4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid] is C₈H₁₈N₂O₄S. From the chemical formula, you can find that one molecule of HEPES consists of eight Carbon (C) atoms, eighteen Hydrogen (H) atoms, two Nitrogen (N) atoms, four Oxygen atoms, and one Sulfur (S) 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 HEPES molecule by multiplying its atomic weight by its number.

Number of Carbon atoms in HEPES: 8
Atomic weight of Carbon (C): 12.0107
Total weight of Carbon atoms in HEPES: 12.0107 x 8 = 96.0856

Number of Hydrogen atoms in HEPES: 18
Atomic weight of Hydrogen (H): 1.008
Total weight of Hydrogen atoms in HEPES: 1.008 x 18 = 18.144

Number of Nitrogen atoms in HEPES: 2
Atomic weight of Nitrogen (N): 14.00674
Total weight of Nitrogen atoms in HEPES: 14.00674 x 2 = 28.01348

Number of Oxygen atoms in HEPES: 4
Atomic weight of Oxygen (O): 15.9994
Total weight of Oxygen atoms in HEPES: 15.9994 x 4 = 63.9976

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

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

Molecular weight of HEPES: 96.0856 (Carbon) + 18.144 (Hydrogen) + 28.01348 (Nitrogen) + 63.9976 (Oxygen) + 32.066 (Sulfur) = 238.30668

So the molecular weight of HEPES is 238.30668.

HEPES [4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid] [C₈H₁₈N₂O₄S] 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
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See also:

• Hydrogen chloride molecular weight calculation