how was chemistry paper 22

[Rvzie]

nh3+h20====== Hno3+h2??????

nh3+h20====== Hno3+h2??????

it is NH2^+ OH^-

 

[Haider2011]

Nope

I was correct
Cambridge are making confuse

 

[Haider2011]

Wow

What is the right Answer
Mine Organic part was superb
24 hour past now openly discuses
periodicity was seem difficult for me

 

[Haider2011]

there was no chiral carbon (at least i hope there wasnt cuz thats what i wrote)

after the box in no.4, they asked for the structural formula of the compound formed when the crotyl alcohol ( or something like that) reacted with PCl5, i think it was probably the OH replaced by Cl. after that, there was a skeletal formula for an aldehyde, calculating empirical formula which came C7H14O for me (not sure if this is correct)

yes With PCl 5 only replace -OH with Cl b/c we read the rxn of -OH with Pcl5 not with alkene
with K2cr2O7 no rxn with Alkene but -OH replaced with -HO b/c they asked for heat under reflux
oxidation of Alkene is with KMnO4 not with K2Cr2O7

 

[s_hithappens]

it is NH2^+ OH^-

what the hell is this.

 

[s_hithappens]

KMnO4= alkene oxidized and 2 OH's added to the crotyl alcohol
PCl5= OH replaced by Cl
NaBH4= no reaction?
h2 and Ni catalyst= 2 H's added across double bond

there was another one, i dont remember, what was it??

 

[Muddy]

KMnO4= alkene oxidized and 2 OH's added to the crotyl alcohol
PCl5= OH replaced by Cl
NaBH4= no reaction?
h2 and Ni catalyst= 2 H's added across double bond

there was another one, i dont remember, what was it??

It was k2Cr2O7/H+ heat under reflux and in this one primary alcohol was oxidised to carboxylic acid ..

 

[s_hithappens]

shit i wrote aldehyde

 

[SB29597]

What is the right Answer
Mine Organic part was superb
24 hour past now openly discuses
periodicity was seem difficult for me

I loved periodicity. i think organic was okay- i got most stuff.

 

[SB29597]

WHAT WILL BE THE MOST LIKELY QUESTION FOR PAPER31 SUMMER 2013

How do we know? -_-

 

[SB29597]

yup. OH is replaced by a Cl. Don't remember my empirical formula.

I got something like C7H14O or something

 

[SB29597]

can someone tell me what the mass of NaNO3 was? I got 2.30g at first but then I redid it and got 1.4ish grams

Yep. I got that too 1.4 something divided by 1.69 and multiplied by 100 giving 91.22%

 

[Jinkglex]

Is the 24 hr period up now then?

 

[s_hithappens]

who cares

 

[SB29597]

Is the 24 hr period up now then?

Yes ma'am it's up. -_-
P.S. No one really cares anyway.

 

[Jinkglex]

Yes ma'am it's up. -_-
P.S. No one really cares anyway.

1) Not a ma'am.
2) I'd rather be sure.

Anyway. I think the NH3 weak base was NH3 + H2O -> NH4 + OH with a suitable description of how a weak base is one which does not dissociate completely in water.

With excess Ammonia whatever the compound was [the one with CL on the ends and OH in between] was getting NH2 on the two ends and replaced the OH, it was a nucleophilic substitution.

K2Cr2O7/H+ made carboxylic acid out of the alcohol, whereas KMnO4 cold dilute made a diol.

 

[plantaholic]

Oh shit bro, my friends got around 91 aswell. i screwed it up and got around 23 somthing *cries*

sheesh!
I got 23 too :/

 

[plantaholic]

Oh shit bro, my friends got around 91 aswell. i screwed it up and got around 23 somthing *cries*

sheesh!
I got 23 too :/

 

[Jinkglex]

Contact process requirements were Vanadium {V} Oxide catalyst, 450C temperature, 1ATM pressure.

Example of period 3 oxide and chloride could be P4O10 which burns with yellow flame and the chloride is PCL5 which leaves behind solution of PH 2.

Aluminium was the covalent chloride which could conduct as well as the cation with the best conductivity.

 

[s_hithappens]

hey nacl conducts too!