Entropy Classes

21/05/2024

Proudly sharing results of my class xii batch of 2024

15/06/2023

15/06/2023

Class of 2023...
Wish you all a beautiful life ahead filled with fun, laughter n success....

17/05/2023

Sharing my Proud moments ...

28/02/2023

Waiting for the response of my students....

23/02/2023

Today 's Target

Alcohols , Phenols and Ethers

1.Phenol is acidic while benzyl alcohol is neutral , why ?
2. What is Rectified spirit and how is it different from Denatured alcohol ?
3. Explain how the -OH group on a benzene ring activates it for electrophilic substitution reaction ?
4. Write the chemical reaction for the following :
(i) Phenol + Br2 - H2O
(ii) Benzyl alcohol + PCL5
(iii) Butan-2-ol + CrO3
5. Write short note on :
(i) Reimer Tiemann reaction
(ii) Kolbe's reaction
6. Starting with phenol how will you synthesize :
(i) Picric acid (ii) Aspirin
7. An organic compound [A] (C6H6O) gives characteristic colour with aq. FeCl3 . When [A]
is treated with CO2 & NaOH at high temp. & pressure compound [B] is obtained. The compound [B] on acidification gives [C] which reacts with acetyl chloride to form [D] , which is a pain killer. Identify A,B,C ,D & give the chemical reactions involved.
8. Aromatic ethers always yield Phenol on hydrolysis, why ?
9. Why do tertiary alkyl halide fail to show Williamson synthesis ?
10. Write the mechanism of dehydration of ethanol at 413 K.

22/02/2023

Today we start with Organic chemistry, from first chapter of Book -2

Haloalkanes & Haloarenes

1. What is an Ambidient nucleophile ? Explain giving example.
2. Choose the correct option and explain the reason
(i) CH3-Cl or CH3-I --reacts faster with Ammonia
(ii) 3-Chloropentane or 3-Chloro-3-methylhexane -- gives racemic mixture in reaction with aqueous NaOH.
3. Give reasons :
(i) Why chlorobenzene cannot form phenol on treatment with aq.KOH while ethanol is formed easily with ethyl chloride
(ii) chloroform is stored in a dark coloured bottle away from sunlight.
4. Define :
(i) Chiral Carbon
(ii) Enantiomers
(iii) Racemic mixture
5. Write the reaction mechanism using curved arrow notations for a reaction between an optically active tertiary alkyl halide and a nucleophile.
6. Why halogenation of Toluene should be carried out in the absence of sunlight ? How will the product formation be affected due to sunlight ?
7.Although Halogens exhibit -I effect, yet electrophilic substitution reaction of chlorobenzene leads to formation of ortho and para derivatives, explain.
8. What are Freons ? Give their use.
9. Write short notes on :
(i) Sandmeyer's Reaction
(ii) Swartz Reaction
(iii) Wurtz Reaction
(iv) Balz Schiemann Reaction
10. Why the products formed are different when an alkyl halide is treated with aq. KOH and alc. KOH ? Explain giving reasons

21/02/2023

Today's Target is Coordination Compounds

1. What is an Ambidentate Ligand ? Give an example.
2. Which of these is more stable and why : [Cr(en)3]+3 or [Co(NH3)6]+3.
3. Write the formula of geometric isomer of [Co(H2O)5(SO4)]Cl . Also give suitable chemical test to distinguish between these two compounds .
4. Why all octahedral complexes of Ni alwi paramagnetic ?
5. Using Valence Bond Theory identify the type of hybridization, magnetic behaviour and nature of the following complexes :
(i) [Co(ox)3]-3
(ii) [Fe(CO)5]
6. What is the Spectrochemical Series? What criteria is used to create this series ?
7. Give the formula and IUPAC name of the coordination entity formed when cobalt chloride is dissolved in ammonia and the resultant solution gives 2 mol of AgCl precipitates on treatment with silver nitrate.
8. A metal ion M+3 with d6 configuration is bonded to three bidentate ligands , write the configuration in terms of t2g and eg if ∆o > P.
9. Draw a well labelled diagram of Crystal Field splitting in Octahedral Complexes.
10. Answer the following
(i) Vitamin B-12 is also called as___________
(ii) what is the relationship between [Co(NH3)6] [Cr(CN)6] and [Cr(NH3)6] [Co(CN)6]
(iii) which compound is used for treatment of tumors

19/02/2023

Today we start with Inorganic chemistry, so ten important questions from ....
d & f Block Elements

1. Why is Ag considered as a transition element while Cd is not ?
2. Why is Zn a low melting metal as compared to iron ?
3. Why are Cu+1 salts unstable in aqueous medium ?
4. Why do transition element exhibit their highest oxidation states in their oxides and oxoanions ?
5. Identify which element exhibit the following property :
(i) Highest oxidation state
(ii) single oxidation state
(iii) maximum number of unpaired electrons in first series
(iv) positive E° value in the first transition series
6. Cr+2 & Mn+3 both have (3d)4 configuration , still Cr is reducing while Mn is oxidising, explain
7. Write the chemical equation when :
(i) KMnO4 is heated
(ii) pH of potassium dichromate solution is increased
8. Define Lanthanoid Contraction also discuss it's consequences
(two points)
9. Why is Eu+3 a good oxidising agent and Ce+3 a good reducing agent ?
10. Why do transition elements show variable oxidation states?

18/02/2023

Today it's
Chemical Kinetics
1. What is the difference between Order and Molecularity of a reaction ?
2. What will burn faster powdered coal or a lump of coal ? Justify your answer
3. What is a Pseudo first order reaction ? Give an example.
4. Define Half-Life of a reaction. Prove that half life of a first order reaction is independent of initial concentration of the reactant .
5. How can you convert a second order reaction to a first order reaction ?
6. Define Activation Energy. How is it different from Threshold Energy , illustrate using a diagram for endothermic reaction.
7. How does a catalyst influence the rate of a reaction ? Explain its effect on Ea .
8. Prove that t(99%) = 2 . t(90%)
for a first order reaction.
9. What fraction of a reactant is left after 6 hrs , in a first order reaction whose t(1/2) = 2 hrs.
10. What is the effect of increasing in temperature on a chemical reaction ? Give the expression relating the temperature with the rate of a reaction.