# Rauenthalite [Ca3(AsO4)2.10H2O] Molecular Weight Calculation

The molecular weight of Rauenthalite [Ca3(AsO4)2.10H2O] is 578.22639. Calcium arsenate [Ca3(AsO4)2] is an inorganic compound of three elements: Calcium (Ca), Arsenic (As), and Oxygen (O). The decahydrate form of Calcium arsenate, Rauenthalite [Ca3(AsO4)2.10H2O], also contains ten water (H2O) molecules. The molecular weight of Rauenthalite is 578.22639 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: Rauenthalite [Ca3(AsO4)2.10H2O] Molecular Weight Calculation

Step 1: Find out the chemical formula and determine constituent atoms and their number in a Rauenthalite molecule.
You will know different atoms and their number in a Rauenthalite molecule from the chemical formula. The chemical formula of Rauenthalite is Ca3(AsO4)2.10H2O. From the chemical formula, you can find that one molecule of Rauenthalite has three Calcium (Ca) atoms, two Arsenic (As) atoms, eight Oxygen (O) atoms, and ten water molecules.

Step 2: Find out the atomic weights of each atom (from the periodic table).
Atomic weight of Calcium (Ca): 40.078 (Ref: PubChem-20, Ciaaw-calcium)
Atomic weight of Arsenic (As): 74.921595 (Ref: Jlab-ele033, ciaaw-arsenic)
Atomic weight of Oxygen (O): 15.9994 (Ref: Jlab-ele008)
Molecular weight of Water [H2O]: 18.0154

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

Number of Calcium atoms in Rauenthalite: 3
Atomic weight of Calcium (Ca): 40.078
Total weight of Calcium atoms in Rauenthalite: 40.078 x 3 = 120.234

Number of Arsenic atoms in Rauenthalite: 2
Atomic weight of Arsenic (As): 74.921595
Total weight of Arsenic atoms in Rauenthalite: 74.921595 x 2 = 149.84319

Number of Oxygen atoms in Rauenthalite: 8
Atomic weight of Oxygen (O): 15.9994
Total weight of Oxygen atoms in Rauenthalite: 15.9994 x 8 = 127.9952

Number of water (H2O) molecules in Calcium chloride monohydrate: 10
Molecular weight of water: 18.0154
Total weight of water in Calcium chloride monohydrate: 18.0154 x 10 = 180.154

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

Molecular weight of Rauenthalite: 120.234 (Calcium) + 149.84319 (Arsenic) + 127.9952 (Oxygen) + 180.154 (water)= 578.22639

So the molecular weight of Rauenthalite is 578.22639.

Rauenthalite [Ca3(AsO4)2.10H2O] Molecular Weight Calculation

## REFERENCES:

• PubChem-20: https://pubchem.ncbi.nlm.nih.gov/element/20
• Ciaaw-calcium: https://www.ciaaw.org/calcium.htm
• Jlab-ele008: https://education.jlab.org/itselemental/ele008.html
• Jlab-ele033: https://education.jlab.org/itselemental/ele033.html
• https://www.ciaaw.org/arsenic.htm

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