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Normality Definition

The concentration of a solute in a solution is represented using normality. The normality's SI unit is gram per litre. It is primarily used to measure the presence of reactive species in a solution, as part of titration processes, particularly in acid-base chemistry situations. Meq L-1 is also utilized to measure normality. Precipitation, redox, and acid-base chemical reactions all generally utilize normality.

Normality Definition
  1. In precipitation reactions, normality determines the number of ions expected to precipitate in a particular reaction.
  2. In redox reactions, normality determines the number of electrons that are reducing or oxidizing chemicals.
  3. In acid-base chemistry, normality is typically employed to estimate concentrations.

Normality formula

  • Normality = [volume of solution in litres] - 1 * Number of gram equivalents
  • Number of gram equivalents = [Equivalent weight of solute] - 1 * weight of solute
  • N = [Equivalent mass] - 1 * Molarity * Molar mass
  • N = [Equivalent weight × Volume (L) ] * Weight of Solute (gram)
  • N = Molarity × Acidity = Molarity × Basicity

Usage of Normality formula

  1. Acid-base chemistry uses the Normality formula to indicate the number of hydroxide ions in the chemical.
  2. The normality formula specifies the ability to absorb or donate the number of electrons in a redox reaction.

Types of Normality

There are four different kinds of normality:

  1. Seminormal: Seminormal solutions have a normality of 1/2 or N/2.
  2. CentiNormal: CentiNormal solutions have a normality of 1/100 or N/100.
  3. Binormal: Binormal solutions have a normality of 2 or 2 N.
  4. Decinormal: A decinormal solution has a normality of 1/10 or N/10.

Limitations of Normality

Several chemists employ normality in acid-base chemistry to obtain more accurate results. While normality is employed regularly in precipitation and redox processes, it has certain restrictions. These restrictions are as follows:

  1. Molarity or molality are better choices for units because it's a fuzzy measurements.
  2. Normality needs a particular equivalence factor. It is not a predetermined value for a given chemical solution.
  3. It should not be used as a concentration unit in situations other than acid-base, precipitation, and redox processes.

Relation between Normality and Molarity

Normality and molarity are essential and extensively utilized terms in chemistry. It is a chemical concentration unit, just like normality. The number of solute moles per litre of solution is known as molarity. It is also referred to as "molar concentration." Molarity is frequently utilized to estimate pH.

Normality (N) = (Molar mass / Equivalent mass) * Molarity

Normality (N) = Molarity × Acidity= Molarity × Basicity


The total number of moles of solute in solution per litre is called the molarity.

How to Calculate Molarity?

Step 1: Determine how many moles of solute are present in the solution.

Step 2: Determine the solution's volume in litres.

Step 3: Divide the "number of moles " by the " solution's volume".

Molarity = Moles of Solute / Liters of Solution

Advantages of Molarity:

  1. The main advantage of employing molality as a concentration indicator is that it only considers the masses of the solute, which are unaffected by variations in temperature or pressure.
  2. Calculations of molarity are flexible. The solute can be measured in grams, moles, or according to its volume.

Difference between Normality and Molarity

Molarity Normality
1. The amount of moles of a substance present in one litre of a solution is known as its molarity. 1. The gram equivalent weight of a solute in 1L of liquid is called the normality of solution.
2. The unit of molarity is mol/kg. 2. The unit of normality is gram/litre.
3. The temperature, volume, and mobility of solutes affect the molarity of the solution. 3. The reactive species present in liquid affect the normality of the solution.

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