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 Finding symbol of isotops by proton and neutron

Calculation of pKa

Calculation of pKa

 

CHEMISTRY STUDY MATERIAL

TDCHEMISTRY MCQ

How many grams og H2 produced

Partial pressure of hydrogen

Provided the synthetic route from the starting material

Solution:-

Calculation of PH Value

Tollens' Fehling's and Benedict's Test

 Three Visual “Tests” For The Presence of Aldehydes: Benedict’s, Fehlings, and Tollens’ Tests

We’ve seen previously that aldehydes are a functional group that can be oxidized relatively easily to carboxylic acids. For example, oxidation of alcohols with a “strong” oxidant like chromic acid (H2CrO4) results in an aldehyde that is quickly oxidized further to a carboxylic acid.

During this process, the aldehyde is oxidized and the oxidizing agent is reduced. Another way of framing this is to say that the aldehyde is the reducing agent in this process.

 The list of reagents that can be used to oxidize aldehydes to carboxylic acids is loooong. Of these, a few methods stand out in providing a particularly clear visual indication that the reaction has proceeded to completion. 

Three “visual” tests for aldehydes that you might encounter in an introductory organic chemistry lab are the following:

• Fehling's Solution:- where an aldehyde changes the color of a blue Cu(II) solution to red Cu(I)  [as Cu2O]. 
• Benedict's Solution:- a slightly modified version of Fehling’s solution
• Tollens' Test :- where aldehyde oxidation results in a beautiful “mirror” of silver metal to precipitate on the reaction vessel.

Importantly, ketones don’t react under any of these conditions.  The above tests were also a useful way of distinguishing aldehydes from ketones in the dark days before IR and NMR spectroscopy made this routine.

Carbohydrates: Reducing Sugar

What’s a reducing sugar, and why is it important? Here’s a quick summary. Full details in the post below.

Mutarotation

1-Mutarotation Is The Change In Optical Rotation Observed When Pure α- or β- Anomers Are Dissolved In Water (or other solvents)

In our recent post on ring-chain tautomerism, we said that there are two isomers of D-glucose in its 6-membered ring (“pyranose”) form.

These two diastereomers – which, to make matters more confusing, are called “anomers” in the context of sugar chemistry –  differ in the orientation of the hydroxyl group on C-1. (Note that C-1 is a hemiacetal. )

• ➡️In the “alpha” (α) anomer, the OH group on C-1 is on the opposite side of the ring as the chain on C-5.
• ➡️In the “beta” (β) anomer, the OH group on C-1 is on the same side of the ring as the C-5 substituent.

• Each of these two forms can be synthesized and isolated as pure compounds.

  
  • ●The alpha (α)  anomer of D-glucose has a specific rotation of +112 degrees in water.
  • ●The beta (β)  anomer of D-glucose has a specific rotation of +19 degrees. (18.7 actually, but rounding up to 19).

  Here’s the interesting thing. When either anomer is dissolved in water, the value of the specific rotation changes over time, eventually reaching the same value of +52.5°. 

• • ●The specific rotation of α-D-glucopyranose decreases from +112° to +52.5°.
  • ●The specific rotation of β-D-glucopyranose increases from +19° to +52.5°.

  This behaviour is called mutarotation (literally, “change in rotation”).

• Hold on.  Isn’t specific rotation of a molecule supposed to remain the same?

  Yes – if it is indeed the same molecule! 

  And therein lies the answer to the puzzle. For when the solutions whose specific rotations have changed to +52.5° are analyzed, they are found to no longer consist of 100% alpha (α) or 100% beta (β) anomers, but instead a ratio of alpha (α) (36%) and beta (β) (64% ) isomers.

Calculation of pKa

Calculation of pKa

SN1 and SN2 Reaction

SN1 and SN2 Reaction By Nind Kishor Gupta

Oxide, Superoxide, Peroxide

Oxide, Superoxide, Peroxide

UP PGT CHEMISTRY 2019 RESULT

UPPGT 2016 RESULT

         Acidity of Aldehydes and Ketones

           For alkylation reactions of enolate anions to be useful, these intermediates must be generated in high concentration in the absence of other strong nucleophiles and bases. The aqueous base conditions used for the aldol condensation are not suitable because the enolate anions of simple carbonyl compounds are formed in very low concentration, and hydroxide or alkoxide bases induce competing SN2 and E2 reactions of alkyl halides. It is necessary, therefore, to achieve complete conversion of aldehyde or ketone reactants to their enolate conjugate bases by treatment with a very strong base (pKa > 25) in a non-hydroxylic solvent before any alkyl halides are added to the reaction system. Some bases that have been used for enolate anion formation are: NaH (sodium hydride, pKa > 45), NaNH2 (sodium amide, pKa = 34), and LiN[CH(CH3)2]2 (lithium diisopropylamide, LDA, pKa 36). Ether solvents like tetrahydrofuran (THF) are commonly used for enolate anion formation. With the exception of sodium hydride and sodium amide, most of these bases are soluble in THF. Certain other strong bases, such as alkyl lithium and Grignard reagents, cannot be used to make enolate anions because they rapidly and irreversibly add to carbonyl groups. Nevertheless, these very strong bases are useful in making soluble amide bases. In the preparation of lithium diisopropylamide (LDA), for example, the only other product is the gaseous alkane butane.

         

     Werner’s Theory of Coordination Compounds

  

            The fundamental postulates of Werner's theory which was actually a result of dream and made Werner        a noble prize winner in chemistry may be summarized as below.

       1. Metals possess two types of valencies, namely primary (principal) or ionizable valency and secondary (auxiliary) 

     or non–ionizable valency.

  a-  Primary valencies are those which a metal normally exhibit in the formation of its simple salts. Thus, in the formation

     of PtCl₄, CuSO₄ and AgCl the primary valencies of Pt, Cu and Ag are 4, 2 and 1 respectively. Primary valencies are

        satisfied by negative ions.

  b- Secondary Valencies are those which a metal cation exercises towards a neutral molecule or negative group in the 

            formation of its complex ions. Thus, secondary valencies may be satisfied by negative ions, neutral molecules

           having lone electron pair (e.g., H₂O, NH₃, etc.) or even sometimes by some positive groups. In every case, the

           coordination number of the metal must be fulfilled.

       

COORDINATION COMPOUNDS OF COCL3

₃ WITH NH3₃

      In modern terminology the primary valency corresponds to oxidation number and the secondary to coordination
     number. Primary valencies are shown by dotted lines while secondary by thick lines.

2. Every metal has a fixed number of secondary valencies, e.g., cobalt3+ and platinum4+ were recognized to have
 six secondary valencies and copper2+ four. The total number of secondary valencies required by a metal is more
  commonly known as coordination number (C.N).

3. The secondary valencies are always directed towards fixed positions in space about the central metal ions.
   Thus, the number and arrangement of ligands in space determines the stereochemistry of a complex. Thus,
    in case of six secondary valencies the arrangement of secondary valencies may be as directed to the apices of
   a regular octahedral while in case of four secondary valencies arrangement might be either a planar or a tetrahedral
  manner and thus, this postulate predicted the possibilities of a variety of type of isomerism in coordination compounds.
 Remember that primary valencies are non–directional.

Reasoning Questions Of Chemistry UPPGT KVS PGT NVS PGT

          UPPGT UPPGT KVS PGT NVS PGT
     
     Reasoning Questions Of Chemistry

 1.fore nitration aniline is converted into acetanaline?
2. Aromolic ammines are less basic than aliphanic ammines?
3. Silver chiloride dissolve in methyl ammine solution?
4. Phenol does not undergo protosanon readily?
5. Odichlorobengin has lower boiling point than photochiorobenzin?
6. Ammonolysis of alkyl halide does not give a corresponding ammines in pure state.
7. If NO2 or COOH groups is attached to a carbon of benzin ring electrophilic substitution becomes difficults?
8. Halsalkane undergo nucleophilic substitution reaction?
9. Alchohol act as a weck base?
10. Phenol exibit acidic halver?
11. Ether posses dipolemoment even alkyl groups are identical?
12. Carboxylic acids have high boiling point than alcohols of comparable molecular mass?
13. Aloxhydes are more reactive than ketones towards Nucleophilic reagents?
14. Boiling points of eather are lower than isomeric alcohols?
15. Alkin acid is weaker than chioroacetric acids?
16. During the prepration of ammonia aerrivetives of alaehyse &ketones . pH of the reaction is carefully controlled?
17. Presence of acetic anhydense is necessary in the oxidation of tolvene to benzaldehydrade by chromic oxide?
18. Chloroacetic acids has higher pH value than acidic acid?
19. Electrophilic substitution reaction in benzoic acids takes place at metaposition?
20. Alkyl ammines are stronger base than Aryl ammines?
21. Like ammonia ammines are good nucleophiles?
22. In contrast to arenes aliphatic hydrocarbones do not undergo nitration easily?
23. What for quatornavy ammonium salts are widely used?
24. Tolvene is more readily nitrated than benzene?
25. Haloalkanes are more reactive then haloammines?
26. Unlike alcohols ,phenols cannot be easily protonated?
27. Alkyl nitrite have lower boiling point than the corresponding carboxylic acids?
28. Why do aldehydre/ketone behave like polor compounds?
29. Haloarenes are insoluble in water but soloble in benzene?
30. Formalchyde gives cannbard reaction whereas acitaldehyde not?
31. Carboxylic acid do not give the characteristic test of carboxylic group?
32. Haloalkanes undergo nucleophilic substitution whereas haloammines electrophilic substitution?
Why melting point of P dichlorobenzene is greater than that of Odichlorobenzene?
Addition of KCN solution to carbonyl compounds increases the pH of solution
Sodium Bisulfite is used for the purification of Carbonyl Compounds
Boiling point of aldehydes lie in between parent alkanes and corresponding alcohols
Benzaldehyde gives a positive test with Tollens reagent but not give with Fehling solution or Benedict solution.
Carbonyl compound shows nucleophillic addition reaction.

EQUIVALENT WEIGHT CONCEPTS

                   

                         EQUIVALENT CONCEPTS

       Classical Concept of Equivalent weight/ Mass, Equivalent weight, n-factor and Normality for             Acid, Base and Precipitate.

               

CLASSICAL CONCEPT OF EQUIVALENT WEIGHT/MASS :

   

        Number of parts by mass of an element which reacts or displaces from a compound 1.008 parts by mass of hydrogen, 8 parts by mass of oxygen and 35.5 parts by mass of chlorine, is known as the equivalent weight of that element e.g. 

As we can see from the above examples that equivalent weight is the ratio of atomic weight and a factor (say n-factor or  valency factor) which is in above three cases is their respective valencies.

AT CORONA TIME STAY AT HOME , SAFE AT HOME

AT CORONA TIME STAY AT HOME , SAFE AT HOME