Molarity Formula

Molarity Formula 

Molarity Formula is used to calculate the total number of moles of solute per litre of solution. It is highly important for students to understand and learn the difference between a solute and a solvent. The most abundant chemical in the mixture is known as the solvent, and the other components are known as solutes. Molarity Formula is used to calculate the concentration of a solution. It is crucial for students to learn and understand everything they can about the Molarity Formula. The Molarity Formula, its properties, and various numerical problems are discussed in the article.

Molarity Definition

Molarity, also known as “M,” is a measure of the concentration of a solute in a solution. It measures the number of moles of solute dissolved per liter of solution. In layman’s words, molarity indicates how much of a substance (solute) is dissolved in a particular volume of solvent (usually water).

Molarity Formula

Molarity (often denoted as M) is the concentration of the solute in the solution. It is expressed in moles per liter (mol/L) or molar (M). Molarity tells us how many moles of solute are present in one liter of solution.
The molarity formula is given by:

M = n/V

  • M represents the molarity of the solution.
  • n represents the number of moles of solute.
  • V represents the volume of the solution in liters

To calculate the moles of solute, you typically use the formula:

n= molar mass of solute/mass of solute

Here, the “mass of solute” refers to the amount of solute being dissolved in the solution, usually measured in grams (g), and the “molar mass of solute” is the mass of one mole of the solute, expressed in grams per mole (g/mol).

Unit and Calculation of Molarity 

The units of Molarity is mol/liter, which may be shortened and called “molar.” 

For example, the concentration of chloride ions during a reaction of the solution is often written as [Cl−].

Molarity (M)= Solute’s number of moles/volume of solution(liter)

Solute’s number of moles = w/m =weight of solute/molecular weight of solute

Molarity Formula during the precipitation reaction that happens between Pb(NO3 )2 (aq) and KI(aq) will obviously differ given the differente data is different and therefore it shows that the formula is universal. When the two substances are combined these two solutions bright yellow PbI2 (s) precipitate out of the solution. The balanced equation for this reaction is:

Pb(NO3)2 + 2KI(aq) → PbI2 (s) + 2KNO3 (aq)

The total quantity of moles used in the Molarity Formula to understand the solute must be divided by the whole litres of solution.

Factors Affecting Molarity

  • The molarity of a solution is directly proportional to the amount of solute dissolved in the solution.
  • Molarity is inversely proportional to the volume of the solvent. Increasing the volume of the solvent while keeping the amount of solute constant will decrease the molarity, and vice versa. 
  • In some cases, temperature can affect molarity, particularly for solutions where the volume of the solvent changes significantly with temperature. 
  • The chemical nature of the solute and solvent can influence the molarity of a solution. For instance, some solutes may dissolve more readily in certain solvents, leading to higher concentrations

Examples for Molarity Formula 

Example 1: Calculate the molarity of a solution containing 0.5 moles of glucose dissolved in 2 liters of water.


Moles of glucose (n) = 0.5 moles

Volume of solution (𝑉) = 2 liters

Using the formula for molarity:


M = 0.5/2 = 0.25M

Example 2: How many moles of sodium chloride are present in 500 mL of a 0.2 M NaCl solution?


Molarity of NaCl solution (M) = 0.2 M
Volume of solution (V) = 500 mL = 0.5 liters
M = n/V
Substituting the given values:
n=0.2 mol/L×0.5 L =0.1 mol

Example 3: If 25 grams of sulfuric acid are dissolved in enough water to make 500 mL of solution, what is the molarity of the solution?


Given Mass of H2SO4m) = 25 grams
Volume of solution (V) = 500 mL = 0.5 liters
Molar mass of
H 2SO 4 = 98 g/mol
First, we need to find the number of moles of H2So4
N = m/M
N = 25/98 = 0.255
Molarity = 0.255/0.5 = 0.51M

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FAQs (Frequently Asked Questions)

1. What is Molarity?

Molarity is number of moles of solute present per liter of solution

2. What is Unit of Molarity?

The unit of molarity is mol/liter

3. What does Molarity represent?

Molarity represent concentration of solution

4. What is Moalrity Formula?

Molarity Formula is given as n/V where n is number of moles of solute and V is volume of Solution