The molecular weight of Sodium hydroxide (NaOH) is 39.996769.

To calculate molecular weight of any compound, the first step is to know the constituent elements (atoms) and their number in that particular compound. Then calculate the total atomic weight of each element by multiplying its atomic weight by its number. The sum of total atomic weight of all constituent elements will be the molecular weight of the compound. Note that the value of atomic weight may differ from different sources. This is because some sources use conventional atomic weight while others use standard atomic weights. Another important point to consider is the isotopes of an element. Different isotopes of an element will have different atomic weights.

**CALCULATION PROCEDURE**

**Step 1: Find out the chemical formula and determine constituent atoms and their number in a Sodium hydroxide molecule. **From the chemical formula, you will know different atoms and their number in a Sodium hydroxide molecule. Chemical formula of Sodium hydroxide is NaOH. From the chemical formula of Sodium hydroxide, it is easy to find out that there are one Sodium (H) atom, one Oxygen (O) atom and 1 Hydrogen (H) atom in a molecule of Sodium hydroxide.

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

Atomic weight of Sodium (Na): 22.989769 (Ref: pubchem-Sodium)

Atomic weight of Oxygen (O) : 15.999 (Ref: Pubchem-Oxygen)

Atomic weight of Hydrogen (H) : 1.008 (Ref: Pubchem-Hydrogen)

**Step 3: Calculate the total weight of each atom present in Sodium chloride by multiplying its atomic weight by its number. **

Number of Sodium atoms in Sodium hydroxide: 1

Atomic weight of Sodium: 22.989769

Total weight of Sodium atoms in Sodium hydroxide: 22.989769

Number of Oxygen atoms in Sodium hydroxide: 1

Atomic weight of Oxygen: 15.999

Total weight of oxygen atoms in Sodium hydroxide: 15.999

Number of Hydrogen atoms in Sodium hydroxide: 1.008

Atomic weight of Hydrogen: 1.008

Total weight of Hydrogen atoms in Sodium hydroxide: 1.008

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

Molecular weight of Sodium chloride (NaOH):

22.989769 (22.989769 x 1 Sodium) + 15.999 (15.999 x 1 Oxygen) + 1.008 (1.008 x 1 Hydrogen)

So the molecular weight of Sodium hydroxide is 39.996769.

Molecular weight of Sodium Hydroxide (NaOH) | |||

Atoms (elements) in Sodium hydroxide | Number of each atom in Sodium hydroxide | Atomic weight of each atom | Total weight of each atom in Sodium hydroxide |

Na (Sodium) | 1 | 22.989769 | 22.989769 (22.989769 x 1) |

O (Oxygen) | 1 | 15.999 | 15.999 (15.999 x 1) |

H (Hydrogen) | 1 | 1.008 | 1.008 (1.008 x 1) |

Molecular weight of NaOH: | 39.996769 |

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