Lactose (C12H22O11) Molecular Weight Calculation

The molecular weight of Lactose (C12H22O11) is 342.2978.

Lactose (C12H22O11) Molecular Weight CalculationTo 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: Lactose (C12H22O11) Molecular Weight Calculation

Step 1: Find out the chemical formula and determine constituent atoms and their number in a Lactose molecule.
From the chemical formula, you will know different atoms and their number in a Lactose molecule. Chemical formula of Lactose is C12H22O11. From the chemical formula of Lactose, you can find that one molecule of Lactose have twelve Carbon (C) atoms, twenty two Hydrogen (H) atoms and eleven 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 Lactose molecule by multiplying its atomic weight by its number.

Number of Carbon atoms in Lactose: 12
Atomic weight of Carbon: 12.0107
Total weight of Carbon atoms in Lactose: 12.0107 x 12 = 144.1284

Number of Hydrogen atoms in Lactose: 22
Atomic weight of Hydrogen: 1.008
Total weight of Hydrogen atoms in Lactose: 1.008 x 22 = 22.176

Number of Oxygen atoms in Lactose: 11
Atomic weight of Oxygen: 15.9994
Total weight of Oxygen atoms in Lactose: 15.9994 x 11 = 175.9934

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

Molecular weight of Lactose: 144.1284 (Carbon) + 22.176 (Hydrogen) + 175.9934 (Oxygen) = 342.2978

So the molecular weight of Lactose is 342.2978.

Lactose (C5H10O5) Molecular Weight Calculation

Molecular weight of Lactose
Constituent atoms
Number of each atom
Atomic weightTotal weight
Carbon (C)1212.0107144.1284
Hydrogen (H)
22
1.00822.176
Oxygen (O)
11
15.9994175.9934
Molecular weight of Lactose:
342.2978

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

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