Created By : Rina Nayak

Reviewed By : Rajashekhar Valipishetty

Last Updated : Apr 03, 2023

Take the help of the free Equivalent Weight Calculator tool to know the equivalent weight of a chemical reaction in a fraction of seconds. Just you have to give the molecular weight of acid, basicity of acid, unknown value as x and press the calculate button to avail the output.

Molecular Weight of Acid(Mw)
Basicity of Acid(B)
Equivalent Weight of Acid(Ew)

Steps to Calculate Equivalent Weight

Following are the simple steps to find the equivalent weight of a reaction.

  • Get the molecular weight and valency of the reaction.
  • Divide the molecular weight by the valency.
  • Otherwise, find the ratio of molecular weight to the basicity of the acid to check the EW.

Equivalent Weight & Formula

The number of substances that completely react with each other in a reaction is the equivalent weight.

In chemistry, the ratio of molecular weight to valency is called the equivalent weight. It is used to predict the mass of the substance in a reaction and find the normality of the solution.

The formulas to calculate the equivalent weight is

Equivalent weight = molecular weight/valency

molecular weight = equivalent weight x valency

valency = molecular weight/equivalent weight

The equivalent weight of an acid = molecular weight of acid/basicity

Equivalent weight of base = molecular weight of base/acidity

Equivalent weight of salt = molecular weight of slat/total positive valency of metal atoms.


Question1: Find the equivalent weight of H2SO4?


Given that,

H2SO4 → 2H+ + SO4-2

The number of hydrogen ions released by the acid is 2.

So, valency is 2.

Molecular weight of sulphuric acid is 98 grams per mole

Equivalent weight = molecular weight/valency

= 98/2 = 49

Therefore, the equivalent weight of H2SO4 is 49.

Question2: Calculate equivalent weight of aluminium hydroxide?


Given that,

Al(OH)3 → Al+3 + 3 OH-

The released hydroxide ions is 3.

So, the valency is 3

Molecular weight of Al(OH)3 is 78 g/mol

Equivalent weight = molecular weight/valency

= 78/3 = 26

Therefore, the aluminium hydroxide equivalent weight is 26

Stay tuned to Chemistrycalc.Com to know more about the other chemical calculators.

FAQ’s on Equivalent Weight Calculator

1. What is the equivalent weight formula?

The equivalent weight formula is EW = molecular weight/valency.

2. What is meant by equivalent weight?

The equivalent weight of a solution can be defined as the ratio of the molecular weight to the valency of the solute. The number of reactants that completely react with each other in a chemical reaction is called the equivalent weight.

3. How to find the equivalent weight of an element?

To calculate equivalent weight of a reaction, get the molecular weight and basicity of the acid. Divide the molecular weight by the basicity to obtain the weight equivalent.

4. What is the equivalent weight of HCl?

The hydrochloric acid reaction is HCl → H+ + Cl-

Valency is 1 because the number of hydrogen ions in the reaction is 1.

Molecular weight of HCl = 36.45

Equivalent weight = molecular weight/valency

= 36.45/1 = 36.45

Equivalent Weight Calculator