Equivalent Weight of Acids and Bases
The equivalent mass of an acid or base in an acid-base reaction is always equal to the mass that contributes to or interacts with one mole of the hydrogen ion (H+). In a similar manner, the mass that supplies or reacts with one gram mole of electrons (e-) produced in the redox reaction is the substance’s equivalent weight.
Knowing an acid’s molecular weight and the charge present in it helps to calculate its equivalent weight.
For example, take sulfuric acid,
H2SO4 + 2OH− → 2H2O + SO42−
Using a periodic table to get each element’s MW and adding it we get 2(1) + (32) + 4(16) = 98.0, and we can determine the acid’s Molecular Weight.
Because the sulfate ion is left with a charge of 2, we get to know that this acid can give two protons.
Hence, the equivalent weight = 98.0/2 = 49.0
Logic is the same for a base. A proton can be taken up by ammonium hydroxide in solution to form an ammonium ion:
NH4OH + H+ = H2O + NH4+
Ammonium hydroxide’s Molecular Weight is calculated as (14) + (4)(1) + (16) + 1 = 35.0
The equivalent Weight for this molecule is 35.0/1 = 35.0 since just one proton is consumed.
Equivalent Weight
The most commonly used phrase in chemistry is “equivalent weight,” which is also one of the fundamental concepts in physical chemistry. Equivalent weight commonly referred to as a gram equivalent is the mass of one equivalent or the mass of a particular material that will combine with or replace a specific amount of another substance. To say it another way, the mass of a substance that can displace 1.008 grams of hydrogen or 8.0 grams of oxygen or 35.5 grams of chlorine is its gram equivalent or equivalent weight. Let us study the Equivalent Weight in detail in this article.
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