NaOH Molecular Weight

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NaOH Molecular Weight

If you are looking for the molecular weight value of sodium hydroxide, this article will be a helpful read. Here, you will find its illustrated calculation.

Chemistry is the study of molecules and molecular weight is one of the most important parameters to consider, which helps in quantification of lab results. Here, the calculation of molecular weight of Sodium Hydroxide (NaOH), along with its chemical profile, is presented.

Lab work in chemistry is an obscure kind of detective work, in which quantifying things is important. Chemicals need to be made to react in specific proportions, in order to have a desired result in a chemical reaction. That’s why, knowing the molecular weight is necessary as then you can precisely quantify a reaction by taking appropriate ‘moles’ of a compound.

A mole is the molecular weight of a substance expressed in grams. A gram mole of a substance contains 6.023 X 1023 (Avogadro’s Number) molecules. Knowing the calculation of molecular mass makes it simpler to calculate molarity.


To calculate the molecular weight, you need to firstly lookup the atomic weights of its constituent atoms. For that, a knowledge of its molecular formula is necessary. You already know the molecular formula for Sodium Hydroxide which is NaOH. That is the way chemists describe the composition of these compounds. This molecule is composed of one atom of sodium (Na), bonded with an oxygen (O), and a hydrogen atom (H).

Here are the individual atomic weights of sodium, oxygen, and Hydrogen in amu (atomic mass unit).

  • Sodium – 22.98977 amu
  • Oxygen – 15.9994 amu
  • Hydrogen – 1.00794 amu

Molecular weight is the sum of individual atomic weights. So, here is the formula.

Sodium Hydroxide Molecular Weight = (Atomic weight of Sodium) + (Atomic Weight of Oxygen) + (Atomic Weight of Hydrogen) = 22.98977 + 15.9994 + 1.00794 = 39.99711

So, the molecular weight of this chemical is 39.99711. That means, one gram mole of Sodium Hydroxide is 39.99711 gm.

Chemical Profile

Let us know something more about this compound. It’s also known as ‘Caustic Soda’ or ‘Lye’. It is used in making soaps, paper textiles, and detergents. It’s a metallic base and a white solid at normal temperatures in pure form. Being a base, it reacts with acids to form salts. For example, Sulfuric Acid and Sodium Hydroxide react to form a salt.

It is hygroscopic in nature, which means that it easily absorbs moisture from its surroundings, if left in the open. Here are some other vital statistics:

  • Density: 2.13 gm/cm3
  • Melting Point Temperature: 318° C
  • Boiling Point Temperature: 1388° C

Being basic in nature, this compound is used in the neutralization of acids and has many industrial applications. One should never handle solid Sodium Hydroxide directly, without protection, as it can inflict chemical burns on skin tissues. It should never be handled without gloves or eye protection.

All you need to know is the atomic weight of individual elements and the molecular formula. Once you have this data, you just have to add up individual atomic masses to get the molecular weight.

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