Magnesium Sulfate Heptahydrate (Epsom Salt) [MgSO4.7H2O] Molecular Weight Calculation

The molecular weight of Magnesium Sulfate heptahydrate (MgSO4.7H2O) is 246.4764.

Magnesium Sulfate heptahydrate (MgSO4.7H2O) Molecular Weight CalculationMagnesium Sulfate (MgSO4) is an inorganic compound of three elements: Magnesium, Sulfur, and Oxygen. The heptahydrate form of Magnesium sulfate (MgSO4.7H2O, also known as Epsom Salt) also contains 7 water molecules.  The molecular weight of Magnesium Sulfate heptahydrate is 246.4764 which can be calculated by adding up the total weight (atomic weight multiplied by their number) of all its elements and water molecules.

CALCULATION PROCEDURE: Magnesium Sulfate heptahydrate [MgSO4.7H2O] Molecular Weight Calculation

Step 1: Find out the chemical formula and determine constituent atoms and their number in a Magnesium Sulfate heptahydrate molecule.
You will know different atoms and their number in a Magnesium Sulfate heptahydrate molecule from the chemical formula. The chemical formula of Magnesium Sulfate heptahydrate is MgSO4.7H2O. From the chemical formula, you can find that one molecule of Magnesium Sulfate heptahydrate has one Magnesium (Mg) atom, one Sulfur (S) atom, four Oxygen (O) atoms, and seven water molecules.

Step 2: Find out the atomic weights of each atom (from the periodic table).

Atomic weight of Magnesium (Mg): 24.305 (Ref: Jlab-ele012)
Atomic weight of
Sulfur (S): 32.066 (Ref: Jlab-ele016)
Atomic weight of Oxygen (O): 15.9994 (Ref: Jlab-ele008)

Step 3: Calculate the molecular weight of Magnesium Sulfate heptahydrate by adding the total weight of all atoms.

Number of Magnesium atoms in Magnesium Sulfate heptahydrate: 1
Atomic weight of Magnesium: 24.305
Total weight of Magnesium atoms in Magnesium Sulfate heptahydrate: 24.305 x 1 = 24.305

Number of Sulfur (S) atoms in Magnesium Sulfate heptahydrate: 1
Atomic weight of Sulfur: 32.066
Total weight of Manganese atoms in Magnesium Sulfate heptahydrate: 32.066 x 1 = 32.066

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

Number of water (H2O) molecules in Potassium antimonyl tartrate trihydrate: 7
Molecular weight of water: 18.0154
Total weight of water in Potassium antimonyl tartrate trihydrate: 18.0154 x 7 = 126.1078

Step 4: Calculate the molecular weight of Magnesium Sulfate heptahydrate by adding up the total weight of all atoms.

Molecular weight of Magnesium Sulfate heptahydrate : 24.305 (Magnesium) + 32.066 (Sulfur) + 63.9976 (Oxygen) + 126.1078 = 246.4764

So the molecular weight of Magnesium Sulfate heptahydrate is 246.4764.

Magnesium Sulfate heptahydrate [MgSO4.7H2O] Molecular Weight Calculation

Molecular weight of Magnesium Sulfate heptahydrate (MgSO4.7H2O)
Constituent atomsNumber of each atom
Atomic weight
Total weight
Magnesium (Mg)124.30524.305
Sulfur (S)1
32.06632.066
Oxygen (O)4
15.999463.9976
Water (H2O)
7
18.0154126.1078
Molecular weight of Magnesium Sulfate heptahydrate (MgSO4.7H2O):
246.4764

REFERENCES:

  • Jlab-ele012: https://www.ciaaw.org/Magnesium.htm
  • Jlab-ele016: https://education.jlab.org/itselemental/ele016.html
  • Jlab-ele008: https://education.jlab.org/itselemental/ele008.html

See also:

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