# Calcium Chloride Monohydrate (CaCl2.H2O) Molecular Weight Calculation

The molecular weight of Calcium chloride monohydrate [CaCl2.H2O] (CAS Registry Number: 22691-02-7) is 128.9988.

Calcium Chloride [CaCl2] is an inorganic compound of two elements: Calcium (Ca) and Chlorine (Cl). The monohydrate form of Calcium Chloride (CaCl2.H2O) also contains one water (H2O) molecule. The molecular weight of Calcium chloride monohydrate is 128.9988 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: Calcium Chloride monohydrate (CaCl2.H2O) Molecular Weight Calculation

Step 1: Find out the chemical formula and determine constituent atoms and their number in a Calcium chloride monohydrate molecule.
You will know different atoms and their number in a Calcium chloride monohydrate molecule from the chemical formula. The chemical formula of Calcium chloride monohydrate is CaCl2.H2O. From the chemical formula, you can find that one molecule of Calcium chloride monohydrate consists of one Calcium (Ca) atom, two Chlorine (Cl) atoms, and one molecule of water.

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

Atomic weight of Calcium (Ca): 40.078 (Ref: Ciaaw-calcium, Jlab-ele020)
Atomic weight of Chlorine (Cl): 35.4527 (Ref: Jlab-ele017)
Molecular weight of Water [H2O]: 18.0154

Step 3: Calculate the molecular weight of Calcium chloride monohydrate by adding the total weight of all atoms.

Number of Calcium atoms in Calcium chloride monohydrate: 1
Atomic weight of Calcium: 40.078
Total weight of Calcium atoms in Calcium chloride monohydrate: 40.078 x 1 = 40.078

Number of Chlorine atoms in Calcium chloride monohydrate: 2
Atomic weight of Chlorine: 35.4527
Total weight of Chlorine atoms in Calcium chloride monohydrate: 35.4527 x 2 = 70.9054

Number of water (H2O) molecules in Calcium chloride monohydrate: 1
Molecular weight of water: 18.0154
Total weight of water in Calcium chloride monohydrate: 18.0154 x 1 = 18.0154

Step 4: Calculate the molecular weight of Calcium chloride monohydrate by adding up the total weight of all atoms.

Molecular weight of Calcium chloride monohydrate (CaCl2.2H2O): 40.078 (Calcium) + 70.9054 (Chlorine) + 18.0154 (water) = 128.9988

So the molecular weight of Calcium chloride monohydrate is 128.9988.

## REFERENCES:

• Pubchem-20: https://pubchem.ncbi.nlm.nih.gov/element/20
• Ciaaw-calcium: https://www.ciaaw.org/calcium.htm
• Jlab-ele020: https://education.jlab.org/itselemental/ele020.html
• jlab-ele017: https://education.jlab.org/itselemental/ele017.html