Normality in chemistry is one of the expressions to measure the concentration of a chemical solution. It is sometimes referred to as the equivalent concentration of a solution. It is mainly useful as a measure of reactive species in a solution and hence we can use it during titration reactions. This article will explain the Normality and Normality Formula with examples. Let us begin it!

Source: wikihow.com

**Normality Formula**

**Concept of Normality**

As per the standard definition, we may describe it as the number of grams of mole equivalents of solute present in a one-liter volume of a solution. When we say equivalent, then it is the number of moles of the reactive units in a compound.

For most purposes in titration, molarity is the more preferred unit of concentration. If the temperature of an experiment will change, then morality is more useful. Normality tends to be useful during titration calculations.

One can determine the gram equivalent weight by the amount of an ion that reacts. Gram equivalent weight is not a consistent amount creates confusion and hence it leads scientists to use other concentration values. Normality is typically useful in acid-base reactions.

We use symbol N to denote Normality. Some of the other units of normality are also expressed as eq per L or meq per L. The latter one is useful in medical reporting.

**The Formula for Normality**

Normality indicates the concentration of a solution. Since it as the gram equivalent weight per liter of solution. Therefore,

Normality = \(\frac {gram \;equivalent \;weight}{liter \; of \; solution}\)

Titration is the process of gradual addition of a solution with known concentration and volume with another solution of unknown concentration. This will be done until the reaction approaches its neutralization. To find the normality of any acid and base titration, the balanced equation is as follows:

\(N_{1} \timesĀ V_{1} = N_{2} \times V_{2}\)

Where,

- \(N_{1}\) = Normality of the Acidic solution
- \(V_{1}\) = Volume of the Acidic solution
- \(N_{2}\) = Normality of the basic solution
- \(V_{2}\) = Volume of the basic solution

**Solved Examples on Normality Formula**

Q.1: Determine the normality of 0.321-gram sodium carbonate when it is mixed in a 250 mL solution.

Solution:

First, we have to know the formula for sodium carbonate. Then we need to identify that there are two sodium ions for each carbonate ion.

Now, Normality of 0.321 g sodium carbonate,

N = \(Na_{2}CO_{3} \times (\frac {1 mol}{ 105.99 g} \times (\frac {2 eq}{1 mol})\)

N = \(\frac {0.1886 eq}{ 0.2500 L}\)

= 0.0755 N

Thus normality is 0.0755 N.

Q.2: What will be the concentration of citric acid be if 25 ml of the citric acid solution is titrated with 28.12 mL of 0.1718 N KOH?

Solution:

\(N_{1} \timesĀ V_{1} = N_{2} \times V_{2}\)

\(N_{1} \times (25) = (0.1718) \times (28.12 )\)

= 0.1932 N

Therefore, the concentration of citric acid will be 0.1932 N.

Q.3: How to Calculate the Normality?

Solution: There are some steps, which students should follow to calculate the normality.

- Students can follow is to gather information about the equivalent weight of the reacting substance or given solute.
- Then as the second step calculate the no. of gram equivalent of the solute.
- Students should remember then the volume to calculate in liters.
- Finally, the student can compute normality by using the formula as given above.

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