U4 : Chemical Reactivity and Molecular Structure
Assignment
Topic : Acid-Base Theory
Factors Affecting Acidity and Basicity : (1) Resonance Effect /Mesomeric Effect
(2) Inductive Effect
(3) Hydrogen Bond
(4) Hybridisation
(5) Electronegativity
(6) Hyper conjugation ( Alpha - Hydrogen )
Short Questions
1. Give the Name of the Factors that affecting the Acidity and Basicity of the
substances.
2. According to Arhenius Acid-Base therory, Give Acid and Base Definition.
-According to Lowry-Bronsted Acid-Base Theory, Give Acid and Base Definition.
-According to Lewis Acid-Base Theory, Give Acid and Base Definition.
3. What are the Conjugate Acid-base Pair and Give Some Example.
4. What is Acid Constant ( Ka) and Relative Acidity ( pKa). and What happen when Ka
have high value and low value. And What happen when pKa have High value and low
value OR Derive Ka and pKa Value.
5. What is the conjugate base of H2O,Methane and Ethane.
6. Calculate pKa value of 1N aq. Solution of acetic acid (Ka = 1.76 x 10-5 )
[Hint : Pka = - Log10(Ka) ]
Topic : Resonance Effect
Resonance Effect : Delocalization of electron by intraction of lp and Pi
Bond Electron/Pi and Pi Bond Electron/Functional group and Give
Resonance Structure due to this polarity induced ,known as Resonance
Effect ( Resonance Effect is also known as Mesomeric Effect)
-Resonance Effect stabilize the Conjugate anion/base and acidity
increases & basicity decreases.
e.g. Phenol is more acidic than alcohol
, Due to Stabilization acidity increases bcz the negative charge/lone pair
electrons delocalized so negative charge is distributed and form
resonance structure.
Due to Stabilization basicity decreases bcz lone pair electrons
delocalized so lone pair can,t be donated bcz they are in resonance
*Condition for Resonance Effect
(1) Relative Position of atomic nuclei in the contributing structures
should remain unchanged . They only differ in the position of electrons.
(2) The contributing structure should have the nearly same
energy( Lowest Energies contributing significantly to resonance )
Higher Energy in Structure 1 & 2 lower Energy in Structure 3 & 4
( Pointless/unsignificant Contribution ( Significant Contribution to Resonance )
to Resonance Hybrid ) last two structures are valid
Assignment
Topic : Acid-Base Theory
Factors Affecting Acidity and Basicity : (1) Resonance Effect /Mesomeric Effect
(2) Inductive Effect
(3) Hydrogen Bond
(4) Hybridisation
(5) Electronegativity
(6) Hyper conjugation ( Alpha - Hydrogen )
Short Questions
1. Give the Name of the Factors that affecting the Acidity and Basicity of the
substances.
2. According to Arhenius Acid-Base therory, Give Acid and Base Definition.
-According to Lowry-Bronsted Acid-Base Theory, Give Acid and Base Definition.
-According to Lewis Acid-Base Theory, Give Acid and Base Definition.
3. What are the Conjugate Acid-base Pair and Give Some Example.
4. What is Acid Constant ( Ka) and Relative Acidity ( pKa). and What happen when Ka
have high value and low value. And What happen when pKa have High value and low
value OR Derive Ka and pKa Value.
5. What is the conjugate base of H2O,Methane and Ethane.
6. Calculate pKa value of 1N aq. Solution of acetic acid (Ka = 1.76 x 10-5 )
[Hint : Pka = - Log10(Ka) ]
Topic : Resonance Effect
Resonance Effect : Delocalization of electron by intraction of lp and Pi
Bond Electron/Pi and Pi Bond Electron/Functional group and Give
Resonance Structure due to this polarity induced ,known as Resonance
Effect ( Resonance Effect is also known as Mesomeric Effect)
-Resonance Effect stabilize the Conjugate anion/base and acidity
increases & basicity decreases.
e.g. Phenol is more acidic than alcohol
, Due to Stabilization acidity increases bcz the negative charge/lone pair
electrons delocalized so negative charge is distributed and form
resonance structure.
Due to Stabilization basicity decreases bcz lone pair electrons
delocalized so lone pair can,t be donated bcz they are in resonance
*Condition for Resonance Effect
(1) Relative Position of atomic nuclei in the contributing structures
should remain unchanged . They only differ in the position of electrons.
(2) The contributing structure should have the nearly same
energy( Lowest Energies contributing significantly to resonance )
Higher Energy in Structure 1 & 2 lower Energy in Structure 3 & 4
( Pointless/unsignificant Contribution ( Significant Contribution to Resonance )
to Resonance Hybrid ) last two structures are valid
