HOW WAS CHEM P12 2012 ? WHAT ABOUT GT OF THIS PAPER?

[Soulgamer]

i'm afraid it wasnt B.....i think it was A...... because a bronsted lowry base can have 2 definitions:

a proton acceptor
a lone pair electron donor
When NH3 reacts with Ag+ ions it forms a ligand in which it actually donates its lone pairs of electons...so infact it is behaving as a base. for those candidates who made a rote knowledge of "ammonia to ammonium =base " need to realise that even when protons arent involved a substance can be basic.........check out the wikipedia article about base..........

In our course we study that a base is that which accepts H+. A complex forms when AgCl is added to NH3. [Ag(NH3)2]CL
NH3 is only acting as a ligand(donating lone pair) Hence 3 is totally wrong. 2 was correct as Oxidation state state of nitrogen is unchanged ( -3). 1 was correct, dont remember the option, coordinate bond maybe? Hence it was B!

 

[OakMoon!]

i'm afraid it wasnt B.....i think it was A...... because a bronsted lowry base can have 2 definitions:

a proton acceptor
a lone pair electron donor
When NH3 reacts with Ag+ ions it forms a ligand in which it actually donates its lone pairs of electons...so infact it is behaving as a base. for those candidates who made a rote knowledge of "ammonia to ammonium =base " need to realise that even when protons arent involved a substance can be basic.........check out the wikipedia article about base..........

NH3 can be a base without accepting a proton but it can't be a BRONSTED LOWRY base. A bronsted lowry base has to accept a proton to be defined as one.
The one that donates an elctron pair is called a Lewis base. Search that on wikipedia.

NH3 was definitely acting as a base but not as a bronsted lowry base.

 

[Prince III]

Can someone please tell me the Whole question of Agcl and Nh3 ?

 

[Saad Sarfraz]

About that MCQ where we had to tell about compund X. what were the options and the answer?
Compound X was reacted with some oxidizing agent and the only organic product didnot give a positive result with 2,4 dnph and didnot react with acid to form ester, and perhaps some other things.
one option was carboxylic acid.

Plz help my mind is stuck over this.

ans was alkane..other options were ketone and alcohol

 

[fathimaash]

ans was alkane..other options were ketone and alcohol

yes it was alkane......

 

[egy]

yes it was alkane......

r u sure ?? if yes thank u

 

[Saad Sarfraz]

r u sure ?? if yes thank u

I guess pretty sure caz alcohol will be oxidesed to either an aldehdye or carboxylic acid..aldehyde will show +ive response with DNPH..while carboxylic acid will for react with alcohol to form ester...carboxylic acid cant be oxidised so it will react with alcohol..ketone cant be oxidised but still shows +ive test with DNPH..only option left is alkane..

 

[Saad Sarfraz]

Guys question 32,39 ,28 does any one remember. All i remember is that 32 and 39 were pretty easy

 

[Most_UniQue]

r u sure ?? if yes thank u

Yah it was alkane!!

 

[Saad Sarfraz]

Guys the threshold will definitly be around 30-31..it can be higher than this caz the only paper which had higher than this had 33. and in that paper the first 25 mcqs were like really easily while in this paper there were some really conceptual questions in the first 20.. about 4-5..the organic part was defnitly tricky..while section b had about 3 tough ones..so the mean marks for canditates might me around 23 and A around 30-31

 

[littlecloud11]

ans was alkane..other options were ketone and alcohol

Actually it was an alcohol. a tertiary alcohol to b precise. it does not get oxidized so it doesnot react with either DNPH and it cnt react with alcohol to form ester. i dnt remember the other condition but it was definitely alcohol.

 

[mujtabashahnawaz]

Actually it was an alcohol. a tertiary alcohol to b precise. it does not get oxidized so it doesnot react with either DNPH and it cnt react with alcohol to form ester. i dnt remember the other condition but it was definitely alcohol.

They didn't mention the type of alcohol so the answer was alkane!

 

[littlecloud11]

They didn't mention the type of alcohol so the answer was alkane!

well, they didn't mention the type but does tht mean it isn't a Tertiary alcohol. it fit the conditions.
do you remember the other requirement in the question?

 

[mujtabashahnawaz]

But it can be a primary alcohol and on oxidation it will produce an aldehyde or a carboxylic acid. It can be a secondary one too, producing a ketone ; aldehyde and ketone both will give +ve result with 2,4 DNPH so the alcohol one option gets no chance. If they would have said tertiary alcohol, then it was the option

 

[littlecloud11]

But it can be a primary alcohol and on oxidation it will produce an aldehyde or a carboxylic acid. It can be a secondary one too, producing a ketone ; aldehyde and ketone both will give +ve result with 2,4 DNPH so the alcohol one option gets no chance. If they would have said tertiary alcohol, then it was the option

It's actually funny that i dnt even remember the alkane option. I remember seeing a carboxylic acid, a ketone, an alcohol and an alkene. =P

 

[Prince III]

They didn't mention the type of alcohol so the answer was alkane!

LOL good thinking But unfortunately Answer Was Alcohol

 

[Prince III]

Please discuss the paper here : http://www.xtremepapers.com/community/threads/paper-12-chemistry.14554/page-17

And it was ALCOHOL for sure

 

[littlecloud11]

Please discuss the paper here : http://www.xtremepapers.com/community/threads/paper-12-chemistry.14554/page-17

And it was ALCOHOL for sure [/quot

=D

 

[mujtabashahnawaz]

I am still sticking to my option alkane, we will check when marking scheme comes out at the end of this year!

 

[00tanveer]

But was the 3rd option : "3: Ammonia acts as a base. (Bronsted-Lowry not mentioned)" ?