Peroxide Effect and It's Mechanism

 

Addition to HBr to propene (unsymmetrical alkene) follows Markovnikov Rule according to which the negative part of the addendum gets attached to that C atom which possesses lesser number of hydrogen atoms.

Addition  of  HBr  to  unsymmetrical  alkenes  like propene in the presence of light or peroxide takes place  contrary  to  the  Markovnikov  rule.  This  so happens only with HBr but not with HCl and HI. This Addition  of  HBr  to  propane  in  the  presence  of benzoyl peroxide follows Anti-Markownikov Rule or Peroxide effect or Kharash Effect.

 

The secondary free radical obtained in (iii) in the above mechanism happens to be more stable than the primary one hence, explains the formation of 1-bromopropane.

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Question based on Histidine

Question: In a strong acid solution, the amino acid histidine binds three protons. The acid dissociation constants numbered from the weakest acid dissociation are 6.92 × 10^–10, 1.00 × 10^–6 and 1.51 × 10^–2 at 25°C. Calculate the concentrations of the four forms of  histidine (His^–, HisH, HisH₂⁺and HisH₃²⁺) in a 0.1 M solution of histidine at pH 7, assuming that these constants apply at the ionic strength of the solution.

Solution:

Sulphur Dioxide Practice Questions (in Hindi)

सही विकल्प चुनें।
1. प्रीस्टले ने सल्फर डाई ऑक्साइड गैस का निर्माण कैसे किया था?
(क) कार्बन को सांद्र सल्फ्यूरिक अम्ल के साथ गर्म करके
(ख) पारे को सांद्र सल्फ्यूरिक अम्ल के साथ गर्म करके
(ग) तांबे की छीलन को सांद्र सल्फ्यूरिक अम्ल के साथ गर्म करके
(घ) कैल्शियम सल्फाइट की तनु सल्फ्यूरिक अम्ल के साथ अभिक्रिया कराकर
2. निम्न में किसे वायु में जलाने पर सल्फर डाई ऑक्साइड गैस प्राप्त होती है?
(क) गंधक को
(ख) जिंक सल्फाइड को
(ग) पारे को
(घ) (क) और (ख) को
3. जल की उपस्थिति में सल्फर डाई ऑक्साइड गैस हैलोजन का अपचयन करके क्या बनाती है?
(क) सल्फर
(ख) आक्सीजन गैस
(ग) क्षार
(घ) अम्ल
4. निम्न में से किसमें सल्फर डाई ऑक्साइड गैस का उपयोग नहीं किया जाता है?
(क) कीटाणुनाशक के रूप में
(ख) कृत्रिम रेशम बनाने में
(ग) प्रशीतक के रूप में
(घ) प्रतिक्लोर के रूप में
5. अमोनिया का अणुभार कितना है?
(क) 4
(ख) 10
(ग) 14
(घ) 17
6. हैबर विधि में नाइट्रोजन तथा हाइड्रोजन को किस अनुपात में मिलाकर अमोनिया प्राप्त की जाती है?

(क) 3:1

(ख) 1:2
(ग) 1:3
(घ) 2:1
7. निम्न समीकरण में उत्पाद X क्या होगा?
 

(क) N₂
(ख) NO₂
(ग) NH₃
(घ) NH₃ तथा N₂

8. अमोनिया गैस को ठंडा करने पर यह किस रंग के द्रव में बदल जाती है?
(क) लाल रंग के
(ख) नीले रंग के
(ग) हरे रंग के
(घ) रंगहीन
9. द्रव अमोनिया का क्वथनांक कितना होता है?
(क) ￚ208.0℃   
(ख) ￚ33.4℃
(ग) ￚ17.6℃
(घ) ￚ7.0℃
10. सोडियम पर अमोनिया गैस प्रवाहित करने पर क्या प्राप्त होता है?
(क) सोडामाइड तथा हाइड्रोजन गैस 
(ख) सोडियम नाइट्राइड
(ग) सोडियम हाईड्राइड
(घ) सोडियम नाइट्राइड तथा हाइड्रोजन गैस

उत्तरावली
1. (ख) पारे को सांद्र सल्फ्यूरिक अम्ल के साथ गर्म करके
2. (घ) (क) और (ख) को
3. (घ) अम्ल
4. (ख) कृत्रिम रेशम बनाने में
5. (घ) 17
6. (ग) 1:3
7. (ग) NH₃

8. (घ) रंगहीन

9. (ख) ￚ33.4℃

10. (क) सोडामाइड तथा हाइड्रोजन गैस

Bleaching action of Sulfur dioxide

1.     Bleaching action of SO2 is due to:

        (a)  oxidation       (b)  reduction

        (c)   hydrolysis     (d)  its acidic nature

1.     (b)  Sulphur dioxide is a good reductant. In the presence of water, SO2 is able to decolorise substances. Specifically it is a useful reducing bleach for papers and delicate materials such as clothes.

       

        This bleaching effect normally does not last very long. Oxygen in the atmosphere reoxidises the reduceded dyes, restoring the colour.

Vitamin B12

1.     Which of the following statements about vitamin B₁₂ is false?

        (a)  It has a cobalt atom

        (b)  It also occurs in plants

        (c)   It is present in rain water

        (d) It is needs for human body in very small amounts?

Ans.    (c)  Vitamin B₁₂ is not present in rain water. Vitamin B₁₂ is a member of the vitamin B complex. It contains cobalt, and so is also known as cobalamin. It is exclusively synthesised by bacteria and is found primarily in meat, eggs and dairy products. There has been considerable research into proposed plant sources of vitamin B₁₂. Fermented soya products, seaweeds and algae such as spirulina have all been suggested as containing significant B₁₂. However, the present consensus is that any B₁₂ present in plant foods is likely to be unavailable to humans and so these foods should not be relied upon as safe sources. Many vegan foods are supplemented with B₁₂. Vitamin B₁₂ is necessary for the synthesis of red blood cells, the maintenance of the nervous system, and growth and development in children. Deficiency can cause anemia.

Coordination Compounds

Co-ordination compounds: In a complex ion, the central metal ion is surrounded by a number of negative ions or the neutral molecules (known as ligands) which are linked by co-ordinate or dative bonds. Therefore, the complex compounds are often called co-ordination compounds.

Co-ordination number (C.N.): The total number of monovalent (monodentate) ligands or the total number of donor atoms co-ordinated to the central metal atom or ion in a complex, is called co-ordination number of the central metal ion or atom.

For example, in the complex, K3[Al(C2O4)3], the co-ordination number of aluminium ion is six because there are six donor oxygen atoms of three oxalate ions co-ordinated to aluminium ion.

Co-ordination sphere: The central atom or ion along with the co-ordinated ligand ions or molecules in a complex ion, are enclosed in square brackets [   ]; it is collectively called co-ordination sphere. For example in the complex [CO(NH3)5Br]SO4, the five ammonia molecules and one bromide are co-ordinated to central cobalt ion. They are in the co-ordination sphere.