Normality Numerical

aMolarityMolarity (M) is defined as the number of moles of a solute present in per litreof solution.i.e. Molarity = Number of moles of solute

Volume of solution in liter No of moles = mass

molecular weight Molar solution: The solution containing one mole of solute in one litre solutionis called molar solution. For example, if one mole of nitric acid (63 gram) ispresent in one litre of solution, it is called molar solution. Decimolar solution: The solution containing 1/10 mole of a solute in one litresolution is called deci molar solution. For example, if 1/10 mole of nitric acid (6.3gram) is present in one litre of solution, it is called decimolar solution. MolalityMolality (m) is defined as the number of moles of solute present in one kilogramof solvent.i.e. Molality = Number of moles of solute

Mass of of solvent in kilogram Example 1Calculate the molarity of 40g H2SO4 in 200ml solution.Solution:Given, mass of solute =40gVolume of solution =200mlWe know that molar mass of H2SO4=98gAgain, number of moles of H2SO4= Mass of solute

Molecular weight of solute =40g

98g=40

98Also, volume of solution in litres =200

1000=1

5Now, Molarity (M)= moles of solute

litres of solution =40/98

1/5=2.04MExample: 2Calculate the molality if 90g of NaCl is added into 1800 grams of water.Solution:Given, mass of solute =90gMass of solvent =1800gWe know that molar mass of NaCl=58g (approx)Number of moles of NaCl= Mass of solute

Molecular weight of solute =90g

58gMass of solvent in kg=1800

1000=9

5Now, Molality (M)= Moles of solute

Mass of solvent in kg=90/58

9/5=0.86MNormal solution (1N)The solution containing one equivalent of solute in one litre of solution is called normal solution. aEquivalent mass of acid = Molar mass of acid

Basicity (Here, basicity means number of replaceable hydrogens)aEquivalent mass of base = Molar mass of base

Acidity (Here, acidity means the number of replaceable hydroxyl ions)

Normality = n × M where n= n factor (basicity or acidity) M = molarity

For example, • if 36.5g of hydrochloric acid (one equivalent) is present in one litre of solution, then it is called normal solution of HCl. • if 49g of sulphuric acid (one equivalent) is present in one litre of solution, then it is called normal solution of sulphuric acid. Decinormal solution (N/10) The solution containing 1/10 equivalent of solute in one litre of solution is called decinormal solution. For example, • if 3.65g of hydrochloric acid (N/10 equivalent) is present in one litre of solution, then it is called decinormal solution of HCl. • if 4.9g of sulphuric acid (N/10 equivalent) is present in one litre of solution, then it is called decinormal solution of sulphuric acid. Calculate the normality of the following.a. 4 M of H2SO4.b. 12.5g of calcium carbonate in 200ml of solution a. Solution:Given, Molarity of the solution (M)=4n factor of H2SO4=2As we know, Normality a(N)=n×M=2×4=8 b. Given, Mass of solute =12.5gMolar mass of calcium carbonate =100g"n" factor of calcium carbonate =2Solution =200mlEquivalent mass of calcium carbonate = Molar mass

"n" factor =100

2=50Normality (N)= Mass of solute in gram

Equivalent mass ×1000

Volume of solution in ml Normality (N)=12.5

50×1000

200Normality (N)=1.25N

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