Advertisements
Advertisements
The following questions are case-based questions. Read the passage carefully and answer the questions that follow:
|
Nucleophilic Substitution: Influences of solvent polarity: The reaction rate (SN2) of 2-bromopropane and NaOH in ethanol containing 40% water is twice slower than in absolute ethanol. Hence the level of solvent polarity has an influence on both SN1 and SN2 reactions but with different results. Generally speaking, a weak polar solvent is favourable for SN2 reaction, while a strong polar solvent is favourable for SN1. Generally speaking, the substitution reaction of tertiary haloalkane is based on SN1 mechanism in solvents with a strong polarity (for example ethanol containing water). |
Answer the following questions:
(a) Why racemisation occurs in SN1? (1)
(b) Why is ethanol less polar than water? (1)
(c) Which one of, the following in each pair is more reactive towards SN2 reaction? (2)
(i) CH3 – CH2 – I or CH3CH2 – Cl
(ii)
OR
(c) Arrange the following in the increasing order of their reactivity towards SN1 reactions: (2)
(i) 2-Bromo-2-methylbutane, 1-Bromo-pentane, 2-Bromo-pentane
(ii) 1-Bromo-3-methylbutane, 2-Bromo-2-methylbutane, 2-Bromo-3- methylbutane
Concept: Hydrocarbons: Alkanes >> Reactions of Haloalkanes - Nucleophilic Substitution Reactions
Account for the following:
Helium is used in diving apparatus.
Concept: P - Block Group 18 Elements >> Concept of Group 18 Elements
Draw the structures of the following molecules: XeF2
Concept: P - Block Group 18 Elements >> Concept of Group 18 Elements
Account for the following:
N2 is less reactive at room temperature.
Concept: Concept of Group 15 Elements
Draw the structures of the following: H4P2O7 (Pyrophosphoric acid)
Concept: p-Block elements of Group 15 Elements >> Oxoacids of Phosphorus
What happens when
H3PO3 is heated ?
Write the reactions involved.
Concept: p-Block elements of Group 15 Elements >> Phosphine
Write the mechanism of the following reaction:
Concept: Chemical Reactions of Alcohols and Phenols >> Reactions Involving Cleavage of Carbon–Oxygen (C–O) Bond in Alcohols
Write the main product(s) in each of the following reactions:
Concept: Chemical Reaction of Ethers - Cleavege of C-O Bonds
Write the main product(s) in each of the following reactions:
Concept: Methods of Preparation of Alcohols
Write the main product(s) in each of the following reactions:
Concept: Chemical Properties of Phenol
Account for the following :
Ozone is thermodynamically unstable.
Concept: P - Block Group 16 Elements >> Ozone
Account for the following : Solid PCl5 is ionic in nature.
Concept: p-Block elements of Group 15 Elements >> Phosphorus Halides
Account for the following:
Fluorine forms only one oxoacid HOF.
Concept: P - Block Group 17 Elements >> Oxoacids of Halogens
Draw the structure of BrF5
Concept: P - Block Group 17 Elements >> Interhalogen Compounds
Compare the oxidizing action of F2 and Cl2 by considering parameters such as bond dissociation enthalpy, electron gain enthalpy and hydration enthalpy.
Concept: Concept of Group 17 Elements
Write the conditions to maximize the yield of H2SO4 by contact process.
Concept: P - Block Group 16 Elements >> Sulphuric Acid
Arrange the following in the increasing order of property mentioned :
H3PO3, H3PO4, H3PO2 (Reducing character)
Concept: Concept of Group 15 Elements
Write the structures of A, B, C, D and E in the following reactions:
Concept: Chemical Properties of Phenol
What is the basicity of H3PO4?
Concept: p-Block elements of Group 15 Elements >> Oxoacids of Phosphorus
Name the reagents used in the following reactions:
Concept: Methods of Preparation of Alcohols
