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Monday 30 April 2012

Organic Chemistry book links

Inorganic Chemistry books link

Wednesday 18 April 2012

The E2 reaction – Second Order Elimination


1.     Does Steric Hinderance affect this reaction? 
 
Ans.    Steric hinderance does not greatly affect E2 reactions.  Therefore, highly substituted carbon chains,   which form the most stable alkenes, will undergo E2 easily.

2.    What is the geometry of the intermediate?

Ans. The intermediate form an anti-periplanar geometry.
 
3.     Why is it called a second order reaction?
 
      Ans.   It is called second order because the rate depends on both the substrate and the base .


4.     Can rearrangement occur?  

     Ans. Since E2 does not go by carbocation intermediate, no rearrangements can occur.

 
5.    What type of base does this reaction favor? 

Ans.  A strong base is favored in this reaction because it is better able to remove a proton.
 
6.    What type of substrate works best in this reaction? 

Ans. Highly substituted substrates will work the best in this reaction:3o > 2o > 1o > methyl
Because a good base has more difficulty reaching the carbon for substitution

Sunday 8 April 2012

Questions

1. Which of the following substances cannot be broken down by ordinary chemical reactions?
a) water c) carbon dioxide b) gold d) glucose

2. Which of the following substances does not possess uniform composition?
a) pure water b) salt water c) helium gas d) salad

3. Which of the following is made up of only one type of atom?
a) NO b) He c) CO d) MgS

4. Which of the following represents a mixture?
a) NaCl(s) b) NaCl(l) c) NaCl(g) d) NaCl(aq)

5. Which of the following shows a ternary compound?
a) CO b) NaCl c) NH3 d) NaNO2

Sunday 1 April 2012

IISC 2009

Osmotic Pressure


Q.1    Why a person suffering from high blood pressure is advised to take minimum quantity of common salt ?
Ans.    Osmotic pressure is directly proportional to the conc. of solutes. Our body fluid contain a number of solutes. On taking large amount of salts, ions enter the body fluid there by raising the conc. of the solutes. As a result osmotic pressure increases which may rapture the blood cells.
Q. 2     Chloro acetic acid is a monoprotic acid and has Ka = 1.36 × 10–3. Calculate b. p. of 0.01 M aqueous soln ? (Kb = 0.51 k kg/mol)
Ans.    Kb = 0.51 k kg/mol
            a  = Ka / C
                = 1.36 × 10–3 / 0.01
                = 0.3687
              i = 1 + a
                = 1 + 0.3687 = 1.3687
            DTb = i × Kb m
                 = 1.36 × 10–2 × .51
                 = 0.0069 °C
Q. 3   Which colligative property is preferred for the molar mass determination of macro molecules ? Why ?
Ans.    Osmotic pressure is preferred over all other colligative properties because :
            (a)    even in dil. soln the o. p.values are appreciably high and can be measured accurately.
            (b)       o. p.can be measured at room temp. on the other hand elevation in B. P. is measured at high temp. where the solute may decompose. The depression in freezing point is measured at low temp.

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