# Normality – Formula, Definition, and Examples

## Normality Formula

Normality Formula in chemistry is one of the important terms. Thus, we use it to measure the concentration of a solution. Similarly, its symbol is ‘N’ and is the equivalent concentration of a solution.

Primarily, it is useful as a measure of reactive species in a solution. Further, during titration reactions. Moreover, sometimes it is used in situations involving acid-base chemistry.

Similarly, gram equivalent weight has to be determined by the amount of an ion that which reacts. Further, this can be changed depending on the reaction.

Thus, due to this fact that the gram equivalent weight is not a consistent amount creates confusion. Further, it leads scientists to use other concentration values. Similarly, in this topic, we shall study the normality formula in detail.

### Definition of Normality

We describe it as the number of gram or mole equivalents of solute which are present in one litre of a solution. Similarly, normality is mainly used in three common situations:

1. To determine the concentrations in acid-base chemistry.
2. Used in precipitation reactions to measure the number of ions which are likely to precipitate in a given reaction.
3. It is used in redox reactions to find the number of electrons which a reducing or an oxidizing agent can donate or accept.

### Normality Formula

Normality (N) = $$\frac{Number of eq. gram}{volume of the solution in liters}$$

Where,

Number of gram equivalents = $$\frac{Weight of solute}{Equivalent weight of solute}$$

Thus,

N = $$\frac{Weight of Solute (gram)}{Equivalent weight × Volume (in liter)}$$

We can also calculate it using Molarity as:

N = $$\frac{Molarity × Molar mass}{Equivalent mass}$$

N = Molarity × Basicity = Molarity × Acidity

### How to Calculate Normality?

The following are the steps to calculate the normality:

1. Find the information about the equivalent weight of the reacting substance or the solute.
2. Find out the number of gram equivalent of solute by calculation.
3. Calculate the volume in litres.
4. Then calculate normality using the formula.

We may also express Normality as eq/L i.e. equivalent per litre.

### Normality Problems

Example.1: Calculate the normality of 0.321 g sodium carbonate when it mixes in a 250 mL solution.

Solution:

First, we need to know or write the sodium carbonate formula. After doing this, we can spot that two sodium ions are present for every carbonate ion. Now solving the problem will be easy.

N of 0.321-gram Sodium Carbonate

The chemical formula is Na2CO3

N=  Na2CO3 × $$\frac{1 mol}{105.99 g}$$ × $$\frac{2 eq}{1 mol}$$

N = $$\frac{0.1886 eq}{0.2500 L}$$

N = 0.0755 N

Example.2: Calculate the normality of NaOH solution formed by dissolving 0.2 gm NaOH to make 250 ml solution.

Solution:

Normality (N) = $$\frac{number of Gram Equivalent of solute}{Volume of Solution in litre}$$

Number of Gram Eq. of the Solute = $$\frac{weight}{Equivalent weight}$$

Now, Equivalent weight= Molar Mass n =23+16+11=40

So, N = $$\frac{No. of gram eq. mass}{Vol (liter)}$$

= $$\frac{Weight}{Equivalent weight × 1000 / V (in ml)}$$

= $$\frac{2}{40}$$ x $$\frac{1000}{250}$$

= 0.2 N

### Solved Question for You

Q: How can one differentiate Normality and Molarity?

Ans: Morality is the number of moles of solute per litre of solution, whereas Normality is the number of grams equivalent of solute per litre of solution.

Also, Molarity is a measurement of the moles in the total volume of the solution, whereas Normality is a measurement of the gram equivalent in relation to the total volume of the solution.

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