The molecular weight of Arsenic triselenide [As₂Se₃] is 386.75619.

Arsenic triselenide [As₂Se₃] is an inorganic compound of two elements: Arsenic (As) and Selenium (Se). The molecular weight of Arsenic triselenide is 386.75619 which can be calculated by adding up the total weight (atomic weight multiplied by their number) of all its elements.

CALCULATION PROCEDURE: Arsenic triselenide [As₂Se₃] Molecular Weight Calculation

Step 1: Find out the chemical formula and determine constituent atoms and their number in an Arsenic triselenide molecule.
From the chemical formula, you will know different atoms and their number in an Arsenic triselenide molecule. The chemical formula of Arsenic triselenide is As₂Se₃. From the chemical formula, you can find that one molecule of Arsenic triselenide consists of two Arsenic (As) atoms and three Selenium (Se) atoms.

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

Atomic weight of Arsenic (As): 74.921595 (Ref: Jlab-ele033, ciaaw-arsenic)
Atomic weight of Selenium (Se): 78.971 (Ref: Jlab-ele034, ciaaw-selenium, Nist-34)

Step 3: Calculate the molecular weight of Arsenic triselenide by adding the total weight of all atoms.

Number of Arsenic atoms in Arsenic triselenide: 2
Atomic weight of Arsenic: 74.921595
Total weight of Arsenic atoms in Arsenic triselenide: 74.921595 x 2 = 149.84319

Number of Selenium (Se) atoms in Arsenic triselenide: 3
Atomic weight of Selenium: 78.971
Total weight of Selenium atoms in Arsenic triselenide: 78.971 x 3 = 236.913

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

Molecular weight of Arsenic triselenide: 149.84319 (Arsenic) + 236.913 (Selenium) = 386.75619

So the molecular weight of Arsenic triselenide is 386.75619.

Arsenic triselenide [As₂Se₃] Molecular Weight Calculation

REFERENCES:

• Jlab-ele033: https://education.jlab.org/itselemental/ele033.html
• ciaaw-arsenic: https://www.ciaaw.org/arsenic.htm
• Jlab-ele034: https://education.jlab.org/itselemental/ele034.html
• ciaaw-selenium: https://www.ciaaw.org/selenium.htm
  
• Nist-34: https://physics.nist.gov/cgi-bin/Elements/elInfo.pl?element=34
  

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