The molecular weight of Sodium phosphate dibasic [Na_{2}HPO_{4}] is 141.9589.

Sodium phosphate dibasic (Na_{2}HPO_{4}), also called Disodium phosphate or disodium hydrogen phosphate, is an inorganic compound of four elements: Sodium, Hydrogen, Phosphorus, and Oxygen. The molecular weight of Sodium phosphate dibasic is 141.9589 which can be calculated by adding up the total weight (atomic weight multiplied by their number) of all its elements.

**CALCULATION PROCEDURE: Sodium phosphate dibasic [Na**_{2}HPO_{4}] Molecular Weight Calculation

_{2}HPO

_{4}] Molecular Weight Calculation

**Step 1: Find out the chemical formula and determine constituent atoms and their number in a Sodium phosphate dibasic molecule.**From the chemical formula, you will know different atoms and their number in a Sodium phosphate dibasic molecule. The chemical formula of Sodium phosphate dibasic is Na

_{2}HPO

_{4}. From the chemical formula of Sodium phosphate dibasic, you can find that one molecule of Sodium phosphate dibasic consists of two Sodium (C) atoms, one Hydrogen (H) atom, one Phosphorus (P) atom, and four Oxygen atoms.

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

Atomic weight of Sodium (Na): 22.98976928 (Ref: Ciaaw-sodium)

Atomic weight of Hydrogen (H): 1.008 (Ref: Lanl-1)

Atomic weight of Oxygen (O): 15.9994 (Ref: Jlab-ele008)

Atomic weight of Phosphorus (P): 30.973761998 (Ref: Jlab-ele015)

**Step 3: Calculate the total weight of each atom in a Sodium phosphate dibasic molecule by multiplying its atomic weight by its number.**

Number of Sodium atoms in Sodium phosphate dibasic: 2

Atomic weight of Sodium (Na): 22.98976928

Total weight of Sodium atoms in Sodium phosphate dibasic: 22.98976928 x 2 = 45.97953856

Number of Hydrogen atoms in Sodium phosphate dibasic: 1

Atomic weight of Hydrogen (H): 1.008

Total weight of Hydrogen atoms in Sodium phosphate dibasic: 1.008 x 1 = 1.008

Number of Phosphorus atoms in Sodium phosphate dibasic: 1

Atomic weight of Phosphorus (P): 30.973761998

Total weight of Phosphorus atoms in Sodium phosphate dibasic: 30.973761998 x 1 = 30.973761998

Number of Oxygen atoms in Sodium phosphate dibasic: 4

Atomic weight of Oxygen (O): 15.9994

Total weight of Oxygen atoms in Sodium phosphate dibasic: 15.9994 x 4 = 63.9976

**Step 4: Calculate the molecular weight of Sodium phosphate dibasic by adding up the total weight of all atoms.**

Molecular weight of Sodium phosphate dibasic: 45.97953856 (Sodium) + 1.008 (Hydrogen) + 30.973761998 (Phosphorus) + 63.9976 (Oxygen) = 141.9589

So the molecular weight of Sodium phosphate dibasic is 141.9589.

Sodium phosphate dibasic [Na_{2}HPO_{4}] Molecular Weight Calculation

Molecular weight of Sodium phosphate dibasic [Na_{2}HPO_{4}] | |||

Constituent atoms | Number of each atom | Atomic weight | Total weight |

Sodium (Na) | 2 | 22.98976928 | 45.97953856 |

Hydrogen (H) | 1 | 1.008 | 1.008 |

Phosphorus (P) | 1 | 30.973761998 | 30.973761998 |

Oxygen (O) | 4 | 15.9994 | 63.9976 |

Molecular weight of Sodium phosphate dibasic [Na_{2}HPO_{4}]: | 141.9589 |

## REFERENCES:

- Lanl-1: https://periodic.lanl.gov/1.shtml
- Ciaaw-sodium: https://www.ciaaw.org/sodium.htm
- Jlab-ele008: https://education.jlab.org/itselemental/ele008.html
- Jlab-ele015: https://education.jlab.org/itselemental/ele016.html