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Qualification => Subject Doubts => GCE AS & A2 Level => Sciences => Topic started by: moon on June 02, 2010, 11:01:54 pm

Title: Chemistry ppr 1 doubts
Post by: moon on June 02, 2010, 11:01:54 pm
can somebody help me in solving ppr1 June. 07 Q16,18,34,39 appreciate ur help.
Title: Re: Chemistry ppr 1 doubts
Post by: nid404 on June 03, 2010, 06:46:44 am
Quote from: moon on June 02, 2010, 11:01:54 pm
can somebody help me in solving ppr1 June. 07 Q16,18,34,39 appreciate ur help.

16) As the size of the atom increases down group 7, the electronegativity decreases and the bonds are held less stongly. Bond enthalpy decreases. Hence C

18) The gas given off will be ammonia. The only compound that can give off  ammonia is D(check the fornula)

34) Rise in temp, increases the rate of forward reaction...implies delta h is positive. Hence only 1

39) There are 3 chiral carbons. 1 is wrong.  2 is right because the alkene could form between any of the  Carbon atom...either the one to the right of OH or to the left. 3 is right cause it's a secondary alcohol and will be oxidised to ketone on reacting with Cr2O7...Cr changes color from orange Cr+6 to green Cr+3
Title: Re: Chemistry ppr 1 doubts
Post by: moon on June 03, 2010, 05:49:47 pm
Thanks a lot nid. i really appreciate your great help.Thanks once again :)
Title: Re: Chemistry ppr 1 doubts
Post by: nid404 on June 03, 2010, 05:50:24 pm
Anytime  :)
Title: Re: Chemistry ppr 1 doubts
Post by: sweetie on June 03, 2010, 08:15:28 pm
need help in Q 10,23,39 of nov04

thanx 4 any help!
Title: Re: Chemistry ppr 1 doubts
Post by: thecandydoll on June 04, 2010, 06:44:50 am
O/N 2007 PAPER 1 Q1/
Title: Re: Chemistry ppr 1 doubts
Post by: thecandydoll on June 04, 2010, 06:58:18 am
What is formed when magnesium and barium nitrate reacts?
Title: Re: Chemistry ppr 1 doubts
Post by: girl_92 on June 05, 2010, 04:34:08 pm
Quote from: thecandydoll on June 04, 2010, 06:58:18 am
What is formed when magnesium and barium nitrate reacts?
magnesium nitrate will be formed displacement reaction
Title: Re: Chemistry ppr 1 doubts
Post by: Chingoo on June 05, 2010, 05:03:56 pm
Quote from: libra_92 on June 05, 2010, 04:34:08 pm
magnesium nitrate will be formed displacement reaction

No. There will be no reaction since Barium is more reactive than Magnesium in the Reactivity Series and cannot be displaced from it's compound by Magnesium.
Title: Re: Chemistry ppr 1 doubts
Post by: girl_92 on June 05, 2010, 05:13:46 pm
Quote from: Chingoo on June 05, 2010, 05:03:56 pm
No. There will be no reaction since Barium is more reactive than Magnesium in the Reactivity Series and cannot be displaced from it's compound by Magnesium.
oops sorry i didnt read properly