Normality and Molarity of a Solution: Similarities and Differences
In chemistry, Normality and Molarity are two important concentrations which are typically measured using two different methods. They both indicate the quantitative assessment of a substance. Measurement of copper concentration can be done by giving it as a concentration measurement.
There are two types of concentration measurements: molarity and Normality. Molarity is by far the most common and preferred unit for describing concentration. Normality is another useful unit for determining concentration, and these two terms are linked.
Therefore, let’s understand these concepts along with the formula for normality and molarity.
Molarity: Definition and Formula
- A compound’s molarity is determined by how many moles are present in a litre of the solution.
- The symbol for molarity is C. Another term widely used for molarity is molar concentration. This is because moles per litre represent a compound’s concentration.
- The measurement of the Molarity is done in molecules per litre (mol/L).
- Molarity is sometimes written as “M”.
- Due to the measurement being taken for a litre, Molarity is measured in terms of liquids (solutions).
Solvents and solutes are the components of a solution. Solutes dissolve in solvents. Therefore, a solution is composed of components of solute and solvent. When talking about Molarity, it refers to how many moles of a particular solute is present in one litre of water.
Therefore, to define the equation of the Molarity,
Molarity = Number of moles/volume of the solution.
Equation of Molarity
Molarity can be calculated by using the following equation.
Molarity = Moles of Solute / Liters of Solution
C = n / V
Where C = Molarity,
n = number of moles
V = volume of the solution.
Volume changes, temperature changes, adding more solutes, and any other factor affecting the solubility of a solute in a solution affect a solution’s molarity. Based on the above equation, the molarity decreases when the volume of solvent is increased.
The temperature directly impacts a solution’s volume. An increase in temperature will lead to an increase in the volume of the solution. The molarity will increase as the number of moles of the solute increases when more solutes are added to the solution.
Normality: Definition and Formula
- The gram equivalent weight of a solute measured in one litre of a solution is the normality of the solution.
- It is also known as the equivalent concentration of a solution.
- As the symbol for Normality is N, the units for Normality are eq/L, where the “eq” represents “equivalents.”
- When calculating on a small scale, the unit meq/L is used. Meq is used to represent milliequivalent.
Acid-base reactions are expressed by the hydronium ion concentration (H3O ) or the hydroxyl ion concentration (OH-) through Normality. In this way, the compound’s Normality is dependent upon the type of reaction. However, the same compound can have different normalities when a different reaction is present.
Normality is a way to measure:
- Redox reactions: As a result of such reactions, electrons are transferred, and atoms are reduced. Reducing or oxidising agents can accept or donate electrons according to the normality.
- Acid-base chemistry: Normality here measures the number of hydroxides or protons reacting with each other. Essentially, it describes the concentration of hydroxide (OH-) and hydronium (H3O ).
- Precipitation reactions: Normality refers to the number of ions going to be precipitated in such reactions.
Molarity and Normality: Relationship
By measuring the number of equivalents of a solute present in a solution, one can convert the Molarity into Normality.
N = M x f
Where N = Normality,
M = Molarity,
f = number of equivalents of solute.
Approximately how many ions or groups of atoms are released in a given reaction is the number of equivalence.
The difference between Molarity and Normality
You can easily understand the difference between Molarity and Normality by using the following table, where the differences are stated based on different factors.
|Other Name||Molar concentration is also referred to as molarity.||Alternatively, Normality is referred to as equivalent concentration.|
|Definition||Molarity is the number of moles a compound has per litre of a solution.||A solution’s Normality is determined by the equivalent gram weight of the solute in one litre of solution.|
|Unit||The unit used to measure the Molarity is mol/L.||The unit of measurement for Normality is the eq/L or the meq/L.|
|Dependency of the Reaction||It does not depend on what type of reaction a solute undergoes to determine a solution’s Molarity.||A solution’s Normality is dependent upon how the solute reacts.|
|Effect of Temperature||A temperature change can affect the Molarity of a solution by increasing its volume.||The temperature does not affect the Normality of the solution.|
|Other Factors||The molarity of a solution varies with temperature, volume, solute solubility, and the number of solutes added to it.||It is dependent on the reactive species present in a solution to determine the Normality.|
Molarity and Normality: When to Use?
The most common method for calculating titration is to use Normality. Molarity is the preferred unit of concentration most of the time. Whenever the temperature of an experiment changes, molality is a good unit to use.
The Process of Converting From Molarity to Normality
The following equation can be used to convert Molarity (M) to Normality (N):
N = M*n
where n is referred to as the number of equivalents
It should be noted that N and M can be the same for some chemical species (n is 1). Conversion is only important if ionisation changes the number of equivalents.
The Molarity and Normality are units that measure the concentration of a given solute. Molarity and Normality both take into account one litre of the solution. Still, their values differ since Molarity takes moles of the solute into account, whereas Normality considers the gram equivalents of the solute.
Therefore, Molarity and Normality are different because Molarity represents the number of moles of a particular compound present within a mixture of compounds. In contrast, Normality means the number of gram equivalents of that compound present within that mixture.
Molarity and Normality have a very close relationship, where Normality is a multiple of Molarity. The concept of Molarity and Normality should be very crisp and clear in your mind. Read it 3-4 times and practice the equation regularly to retain the definition and formula for Normality and Molarity.