Qualification > Sciences

Chemistry doubt

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cashem'up:

--- Quote from: J.Darren on May 23, 2010, 06:47:35 pm ---Isn't that a good thing ??? :o

--- End quote ---
well yea the mcq's are based on the core syllabus but every ppr tends to have few tricky questions which tests both......if u had done only core it  would look gibberish bt havin dne extended it makes sense....... otherwise it be funny if a core dude got A in ppr 1 and 6......nd then couldnt go above C in pp3 lolzzz :P
 ;D ;D ;D

red_911:
hey plzz anyone explain me question 13 pp1 O/N 2009  ???

Vin:

--- Quote from: red_911 on May 24, 2010, 10:39:13 am ---hey plzz anyone explain me question 13 pp1 O/N 2009  ???

--- End quote ---

which variant ??

red_911:

--- Quote from: ~VIN1094~ on May 24, 2010, 10:43:25 am ---which variant ??

--- End quote ---

variant one

Vin:

--- Quote from: red_911 on May 24, 2010, 10:45:34 am ---variant one

--- End quote ---

Ok remember when concentrated NaCl is electrolyzed:
First the solution contains Na+ Cl- and H+ and OH- (from water). The positive inos go to the cathode, and negative ions to the anode.

At the CATHODE
the H+ ions accept electrons, since it is less reactive than Na (always elements which is more reactive 'likes' to stay in the ionic form)
2H+  +  2e-  ---> H2

At the ANODE
the Cl- ions give up the electrons more readily than the OH- ions do.
2Cl-  -->  Cl2  +  2e-

what left in the solution is Na+ and OH- which combine to form NaOH

in your ques ..is 'D' .. the indicator solution turns blue at -ve as NaOH is produced .. Chlorine doesnt  show any change in presence of an indicator solution ;)

jus understand the concept ..

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