Relation between Normality and Molarity: Explanation, Difference and Formula

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The relation between normality and molarity is N = M x n where N refers to normality, M is molarity, and n denotes the number of equivalents. Molarity refers to the concentration of a compound or ion in a solution and normality refers to the molar concentration of only the acid component or the base component of the solution. Moreover, the concentration of a solution impacts how the molecules in the solution collide with one another. A solution’s concentration can be determined in a variety of methods. Normality and Molarity are most often utilized among them.

Table of Content

What is Normality?
What is Molarity?
Relation between Normality and Molarity
How to convert Molarity to Normality
Difference between Normality and Molarity
Things to remember
Previous Year's Questions
Sample Questions

Key Terms: Normality, Molarity, Relation between normality and molarity, solutions, molar concentration, molecules

What is Normality?

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Normality is the gram equivalent of the solute dissolved in the volume of solution in litre. It is expressed as ‘N’. For titration calculations, normality is the most preferable method of measuring concentration. Normal solutions have normality equivalent to unity.

\(Normality = {Number\ of\ mole\ equivalent \over 1L \ of \ solution}\)

The number of ions that react in reaction determines normality. This could differ depending on the reaction that occurs. As a result, the gram equivalent weight does not remain constant. This could result in some ambiguity.

Normality is used to measure:

Redox reactions: In such reactions, transfer of electrons occurs and atoms undergo reduction. Normality refers to the number of electrons that can be accepted or donated by reducing or oxidising agents.

Redox reactions

Acid-base chemistry: Normality here is a measure of hydroxides or protons that react with each other. In other words, it describes the concentration of hydroxide (OH^-) and hydronium (H₃O⁺).

Acid-base chemistry

Precipitation reactions: In such reactions, normality indicates the number of ions that will be precipitated.

Precipitation reactions

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What is Molarity?

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The most frequently used measure of concentration in a solution is called molarity. Molarity is the number of moles of a solute dissolved per litre of solution.

Molarity is denoted by mol/L. It is represented as ‘M’.

\(Molarity = {number\ of\ moles\ of\ solute \over Volume\ of\ solute\ in\ litres}\)

The number of moles of a substance is calculated as follows:

\(Number of Moles = {mass\ of\ substance\over Molecular\ mass\ of \ substance}\)

Molarity changes with the temperature and volume. With the increase in temperature, molarity decreases. On a similar note, when the volume of the solution increases, molarity decreases. When the number of solute increases in the solution, so will the molarity. The molarity of the solution also depends on the solubility of a solute and when any additional substances are added to the solution, the molarity has a direct relationship with the amount of solute in a solution.

Other values of molarity are:

Decimolar: M/10 = 0.1 M
Semimolar: M/2 = 0.5 M
Pentimolar: M/5 = 0.2 M
Centimolar: M/100 = 0.01 M
Millimolar: M/ 1000 = 0.001 M

Relation between Normality and Molarity

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Molarity and normality share a very close relation wherein normality can be described as a multiple of molarity. Whereas molarity refers to the concentration of an ion or compound in a solution, normality is the molar concentration only of the acid component or only the base component of the solution. The equation below defines the relationship between Normality and Molarity:

\(Normality = {Molarity\ \times molar\ mass \over Equivalent\ mass}\)

How to Convert Molarity to Normality?

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As we know that the molarity of a solution is the key to calculating its normality. Therefore the simplest way to convert molarity to normality is:

N=M*n

Where,

N is the number of equivalents

In the case of some chemicals, when n=1, then N and M are the same.

Difference between Normality and Molarity

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Normality	Molarity
It is also called equivalent concentration	It is also called molar concentration.
It is referred to as the number of grams equivalent per litre of solution.	It is referred to as the number of moles per litre of solution.
It is used to measure the gram equivalent in relation to the total volume of the solution.	It is used to measure the ratio between the number of moles in the total volume of the solution.

Things to Remember

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Normality is the gram equivalent of the substance dissolved in the volume of solution in litre.
Normality= gram equivalent of solute/ volume of solution in litre
The most frequently used measure of concentration in a solution is called molarity.
Molar concentration is another term for molarity. In other words, the number of moles of a solute dissolved per litre of solution.
Molarity is denoted by mol/L. It is represented as ‘M’.
Molarity and normality share a very close relation wherein normality can be described as a multiple of molarity.

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Chapter Related Topics
Relation Between Molarity and Molality	Some Basic Concepts of Chemistry	Classification of Matter
Uncertainity in Measurement	Laws of Chemical Combinations	Law of Definite Proportions
Number of Moles Formula	Atomic Mass Of Elements	Law of Multiple Proportions
Atomic Mass Formula	Analytical Chemistry	Cisplatin

Previous Years Questions

Sample Questions

Ques. An example of a solution which is prepared by dissolving 10.2 gms of glucose, C₆H₁₂O₆ in about 405g of water. The volume of the solution is 414ml. find out the concentration in units of molality. (2 marks)

Ans. We know the formula for Molality is

Molality=number of moles of solute/ mass of solvent in kgs

Now we need to find out the moles of glucose. The molar mass of glucose as found is 180.16g/mol.
10.2gm of glucose.1 mole glucose/ 180.16g of glucose = 0.0566 moles of glucose
Now, convert the grams of water in kilograms

405g.1kg1000g=0.405kg

Answer would be Molality=0.0566/0.405=0.140m

Ques. When 2 11 g of sodium hydrogen carbonate is dissolved in 10.0L of water, what is the molarity of the solution? (2 marks)

Ans.

When 211g of sodium hydrogen carbonate is dissolved in about 10L solution it i is 0.251M
Step 1- calculate how many moles of NaHCO₃ are present

211gNaHCO₃=1molNaHCO₃

84.006gNaHCO₃=2.51molNaHCO₃

molarity=number of moles of solute/ Volume of solute in litres

M=2.51,molesNaHCO₃10L=0.251M

Ques. Calculate and find out how many millilitres of a 5.0MCuSO₄ solution are required to make 0.350L of 0.500 M CuSO₄_. (2 marks)

Ans.

35 ML of 5.0MCuSO
4 solution is needed to prepare 0.350L which of 0.500MCuSO₄
Formula M₁V₁=M₂V₂
So (5.00M₁)(V₁)=(0.350M₂)(0.500L)
V₁=0.035L=35ml

Ques. What is the molarity of a solution in which 211 g sodium hydrogen carbonate is dissolved in a 10.0 L solution. (1 mark)
(a) 2.51 M
(b) 2.13 M
(c) 0.333 M
(d) 0.251 M

Ans. The correct option is d. 0.251 M

Ques. A solution of hydrogen peroxide is 15.2% by mass. Find the molarity of the solution which has a density of 1.01 g/mL. (1 mark)
(a) 4.95 M
(b) 5.00 M
(c) 3.72 M
(d) 6.02 M

Ans. The correct option is d. 4.95 M

Ques. What is the molarity of a solution containing 750 ml of solution containing 35 g of MgCO3. (1 mark)
(a) .35 M
(b) .25 M
(c) .55M
(d) 1M

Ans. The correct answer is c. 55M

Ques. What is the relation between normality and molarity? (3 marks)

Ans. Molarity and normality share a very close relation wherein normality can be described as a multiple of molarity. Whereas molarity refers to the concentration of an ion or compound in a solution, normality is the molar concentration only of the acid component or only the base component of the solution. The equation below defines the relationship between Normality and Molarity:

Normality=Molarity*Molar Mass/ Equivalent mass

Ques. What is the difference between Molarity and Molality? (3 marks)

Ans. The difference between Molarity and molality are:

Molarity	Molality
It is the total number of moles of solute per litre of solution	It is the total moles of a solute contained in a kilogram of a solvent
Molarity=(number of moles of solute)/(Volume of solute in litres)	Molality=(number of moles of solute)/(mass of solvent in kgs)
It depends on the volume of the whole solution	Depends on the mass of the solvent
Defined as M	Defined as m
Molarity is measured in moles/liter	Molality has units of moles/kg

Ques. Find the normality of the base if 31.87 mL of the base is used in the standardization of 0.4258 g of KHP? (2 marks)

Ans. 0.4258 g of KHP x (1 eq/204.23g) x (1 eq base/1 eq acid)

= 2.085 x 10^-3 eq base/0.03187 L = 0.6542 N

Normality of the base is 0.6542 N.

Ques. What is the relation between normality and Molality? (1 mark)

Ans. Molality can be defined as the number of moles of solute per kilogram of solvent. Normality is the number of equivalents per liter of solution.

Ques. How do you convert molarity to normality? (2 marks)

Ans. If the Molarity of an acid or base solution is known, it can be easily converted it to Normality by multiplying Molarity by the number of hydrogen (or hydroxide) ions in the acid (or base). For example, a 2 M H₂SO₄ solution will have a Normality of 4N (2 M x 2 hydrogen ions).

Ques. What is the concentration of aluminium in a 3.0 M solution of aluminum sulfate? (1 mark)

Ans. The concentration of aluminium in a 3.0 M solution of aluminum sulfate is 6.0 M Al₃⁺.

Ques. Define molarity, molality and normality of a solution. (4 marks)

Ans. Molarity: It refers to the number of moles, of the solute dissolved per liters of the solution. It represented by the symbol 'M'. It is given as: M = Mass of solute/volume of solution in litres

The unit of Molarity is mol/L.

Molality: It is the number of moles of the solute dissolved in 1 kg of the solvent. It is represented by symbol 'm'. It is given as: m = Moles of solute / Weight of solvent in kg

The unit of molality is mol/kg.

Normality: Normality is the number of gram equivalent of the solute dissolved per litre of solution. It is denoted by N. It is given as: Normality = No. of equivalents of solute / Volume of the solution

The unit of Normality is gram equivalent per litre.

Ques. Molarity and molality of a solution of caustic soda are respectively 11.12 M and 94.12 m. Find the density of the solution. (3 marks)

Ans. Given: Molarity = 11.12 M

Molality(m)= 94.12 m

density = \(M [\frac {1}{m} + \frac{molar mass of solute}{1000}\)

molar mass =40 g

d = \(11.2 [\frac{1}{94.12}+ \frac{40}{1000}]\)

d= 11.12×0.0506

d ≈0.56 g/mol

Ques. How are 0.50 Na₂CO₃ and 0.50 M Na₂CO₃ different? (2 marks)

Ans. Molar mass of Na₂CO₃=106g/mol

Therefore, 0.5 moles of Na₂CO₃ means 0.5×106=53g

0.50M Na₂CO₃ means 0.50 moles of Na₂CO₃, i.e., 53g of Na₂CO₃ are present in 1L of the solution.

Ques. What is the normality of lead (II) nitrate if the density of its 26% (w/w) aqueous solution is 3.105 g/mL? Take the molar mass of lead (II) nitrate to be 331g/mol. (3 marks)

Ans. Consider 100g of solution. It is made up of 26g lead (II) nitrate and 74g water.

Volume of solution, V = 100g/(3.105g/ml) = 32.2061 ml = 0.0322 L

Equivalent weight of lead nitrate = 331/2 = 165.5 g/eq

Number of equivalents, N = 26g/(165.5g/eq) = 0.1571 eq

Normality = N/V = 4.878 N

Ques. Consider 100 ml of 0.3 molar solution formed by dissolving 3.33g of XCl2 in water. What is the molar mass of element X? (Atomic mass of Cl = 35.5) (4 marks)

Ans. Concentration, c = 0.3 mole/L

Volume, v = 100 ml = 0.1 L

Number of moles, n = concentration (mole/L) x volume (L)

n = 0.3 mole/L x 0.1 L = 0.03 moles

0.03 moles of XCl₂ corresponds to 3.33g, then 1 mole contains 3.33/0.03 = 111 g of XCl₂.

Hence, molecular mass = 111 g/mole.

Let x be the atomic mass. Then –

111 = x + 2(35.5)

x = 40g/mole

Ques. Calculate the mole fraction of A if 25g of it is dissolved in 50 moles of B. Given the molar mass of A is 25 g/mole. (3 marks)

Ans. Given,

Mass of A, m_A = 25g

Molar mass of A = 25 g/mole

Number of moles of A, n_A = m_A/M_A = 25/25 = 1 mole

Number of moles of B, n_B = 50 moles

Mole fraction of A, x_A = n_A/(n_A+n_B) = 1/(1 + 50) = 0.0196.

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Relation between Normality and Molarity: Explanation, Difference and Formula

What is Normality?

What is Molarity?

Relation between Normality and Molarity

How to Convert Molarity to Normality?

Difference between Normality and Molarity

Things to Remember

Previous Years Questions

Sample Questions

CBSE CLASS XII Related Questions

1.
In the button cells widely used in watches and other devices the following reaction takes place:
Zn(s) + Ag₂O(s) + H₂O(l) \(\rightarrow\) Zn²⁺_(aq) + 2Ag(s) + 2OH^- (aq)
Determine \(\triangle _rG^\ominus\) and \(E^\ominus\) for the reaction.

2.
Draw the structures of optical isomers of:
(i) \([Cr(C_2O_4)_3]^{3–}\)
(ii) \([PtCl_2(en)_2]^{2+}\)
(iii) \([Cr(NH_3)2Cl_2(en)]^{+}\)

3.
Comment on the statement that elements of the first transition series possess many properties different from those of heavier transition elements.

4.
Write equations of the following reactions:
(i)Friedel-Crafts reaction–alkylation of anisole.
(ii)Nitration of anisole.
(iii)Bromination of anisole in ethanoic acid medium.
(iv)Friedel-Craft’s acetylation of anisole.

6.
Define the term solution. How many types of solutions are formed? Write briefly about each type with an example.

Similar Chemistry Concepts

Comments

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Relation between Normality and Molarity: Explanation, Difference and Formula

What is Normality?

What is Molarity?

Relation between Normality and Molarity

How to Convert Molarity to Normality?

Difference between Normality and Molarity

Things to Remember

Previous Years Questions

Sample Questions

CBSE CLASS XII Related Questions

1. In the button cells widely used in watches and other devices the following reaction takes place:Zn(s) + Ag2O(s) + H2O(l) \(\rightarrow\) Zn2+(aq) + 2Ag(s) + 2OH- (aq) Determine \(\triangle _rG^\ominus\) and \(E^\ominus\) for the reaction.

2. Draw the structures of optical isomers of: (i) \([Cr(C_2O_4)_3]^{3–}\)(ii) \([PtCl_2(en)_2]^{2+}\)(iii) \([Cr(NH_3)2Cl_2(en)]^{+}\)

3. Comment on the statement that elements of the first transition series possess many properties different from those of heavier transition elements.

4. Write equations of the following reactions: (i)Friedel-Crafts reaction–alkylation of anisole.(ii)Nitration of anisole.(iii)Bromination of anisole in ethanoic acid medium.(iv)Friedel-Craft’s acetylation of anisole.

6. Define the term solution. How many types of solutions are formed? Write briefly about each type with an example.

Similar Chemistry Concepts

Comments

SUBSCRIBE TO OUR NEWS LETTER

1.
In the button cells widely used in watches and other devices the following reaction takes place:
Zn(s) + Ag₂O(s) + H₂O(l) \(\rightarrow\) Zn²⁺_(aq) + 2Ag(s) + 2OH^- (aq)
Determine \(\triangle _rG^\ominus\) and \(E^\ominus\) for the reaction.

2.
Draw the structures of optical isomers of:
(i) \([Cr(C_2O_4)_3]^{3–}\)
(ii) \([PtCl_2(en)_2]^{2+}\)
(iii) \([Cr(NH_3)2Cl_2(en)]^{+}\)

3.
Comment on the statement that elements of the first transition series possess many properties different from those of heavier transition elements.

4.
Write equations of the following reactions:
(i)Friedel-Crafts reaction–alkylation of anisole.
(ii)Nitration of anisole.
(iii)Bromination of anisole in ethanoic acid medium.
(iv)Friedel-Craft’s acetylation of anisole.

6.
Define the term solution. How many types of solutions are formed? Write briefly about each type with an example.