CHEM UNIT 2!

[alex]

guys wat do u ppl say will iodometric titration cum 2moro or acid base......
wat r ur predictions and how difficult da ppr is gonna be???//

acid-base imo.

can someone plzzz help me with some questions:

Q10 Q11 Q15 and Q16

http://www.edexcel.com/migrationdocuments/QP GCE Curriculum 2000/June 2011 - QP/6CH02_01_que_20110527.pdf

One more thing, plzzzz provide me with notes on "Mass and infrared spectrometry" i don't understand it at all :'(

10)D
One fragment that butan-1-ol can form is [C3H7]^+ which butan-2-ol cant form. Just draw the displayed formula of both and you can figure it out
11) C
One molecule of 1-2-,dibromoethane with 2 bromine 79 atoms, one with 2 bromine-81 atoms, and one with 1 bromine-79 and 1 bromine-81 atoms
15)ethylamine/ B , ethylamine can be produced from the nucleophilic substitution of ethane but not that of methane. And even if you didnt know that, you can cross the other options out
A+D are definitely formed, and C can also be formed if further substitution occurs , so B is not formed
16)C
because you take 2 measurements (1 for the acid and 1 for the alkali), the uncertainty doubles
so, for the mixture it's +-0.08cm^3
so, 0.08/20 X100= =-0.4

I got a more elaborate explanation if you want

 

[svenas]

What u expect for section C?

 

[alex]

Probably a text about carbon compounds and their effect on the environment and ways to reduce carbon compounds emissions

I hope that we get something about carbon and its allotropes (diamond/graphite/nanotubes/fullerenes) because that hasnt come up in quite awhile

 

[za Shadow]

Q10. D-- because butan-1-ol can be fragmented at CH3CH2CH2 to give an m/e value at 43, which is not possible in butan-2-ol

Q11. C-- not too sure why, but I guess it's because there are 3 main elements, hence there will be 3 molecular ion peaks, since both isotopes of Bromine combine to form one major molecular ion peak for Bromine

Q15. B-- because ethylamine cannot form when the reactant is a methane group. The methane can be repeated when it replaces one H atom from NH3, but it will increase by methyl groups only. 1-methyl, dimethyl, trimethyl etc.

Q16. C-- since the TOTAL percentage error has to be calculated (for measuring out NaOH and acid), multiply the accuracy of the pipette by 2 (i.e. 0.04*2= 0.08). Then divide by the total amount that is measured out (i.e. 10 cm3+ 10 cm3) and multiply by 100, to give +-0.4%

Hope you could understand

Thank you very very much you r a great teacher

 

[za Shadow]

acid-base imo.



10)D
One fragment that butan-1-ol can form is [C3H7]^+ which butan-2-ol cant form. Just draw the displayed formula of both and you can figure it out
11) C
One molecule of 1-2-,dibromoethane with 2 bromine 79 atoms, one with 2 bromine-81 atoms, and one with 1 bromine-79 and 1 bromine-81 atoms
15)ethylamine/ B , ethylamine can be produced from the nucleophilic substitution of ethane but not that of methane. And even if you didnt know that, you can cross the other options out
A+D are definitely formed, and C can also be formed if further substitution occurs , so B is not formed
16)C
because you take 2 measurements (1 for the acid and 1 for the alkali), the uncertainty doubles
so, for the mixture it's +-0.08cm^3
so, 0.08/20 X100= =-0.4

I got a more elaborate explanation if you want

thanks alooooooooootttt great explanations

 

[svenas]

yes .. also check for me http://www.edexcel.com/migrationdoc...um 2000/june2010-qp/6CH02_01_que_20100607.pdf Q19 part div

 

[alex]

^whatever you found in Diii , times it by 10 (i think)

 

[svenas]

^whatever you found in Diii , times it by 10 (i think)

Yes right but why? also check the mcq no.18
Thanks

 

[svenas]

is it like 250/25 i guess

 

[alex]

is it like 250/25 i guess

yes

Question 18:
molecular ion peak is the same since they have the same RFM
The fragmentation pattern is different because of the arrangement of the atoms in the carbon skeleton

 

[svenas]

yes

Question 18:
molecular ion peak is the same since they have the same RFM
The fragmentation pattern is different because of the arrangement of the atoms in the carbon skeleton

Thank you
So I did like 7 papers...what should I do next? Read notes ( like diamond/graphite and organic etc) ?

 

[alex]

Thank you
So I did like 7 papers...what should I do next? Read notes ( like diamond/graphite and organic etc) ?

hmm.. yeah sure. If you have time solve other papers from other boards like AQA. They got some very nice questions for organic chemistry and the halogens

 

[aligatorviper]

Thank you
So I did like 7 papers...what should I do next? Read notes ( like diamond/graphite and organic etc) ?

i guess u shud review urself....search in urself which topics u still hav sum kind of problem n overcum it n den definiyely u shud revise>>>

 

[za Shadow]

plzz help me with some questions i know the answer (from the mark scheme) but need to know the explanation and reason plzzz

http://www.edexcel.com/migrationdoc...0/January 2012 - QP/6CH02_01_que_20120307.pdf
Jan 2012 Q17 and Q20 (C) and 21 (B ii) i didn't understand the explanations for the 2 isomers

http://www.edexcel.com/migrationdoc...2000/June 2012 - QP/6CH02_01_que_20120523.pdf
Jun 2012 Q16

 

[za Shadow]

plzzzzz i need notes on "Mass spectrometer and IR" please i don't understand it yet :/

 

[babar baig]

does anyone have the marking scheme for jan 2013 6ch02?

 

[IsraJ]

does anyone have the marking scheme for jan 2013 6ch02?

here you go

 

[alex]

plzz help me with some questions i know the answer (from the mark scheme) but need to know the explanation and reason plzzz

http://www.edexcel.com/migrationdocuments/QP GCE Curriculum 2000/January 2012 - QP/6CH02_01_que_20120307.pdf
Jan 2012 Q17 and Q20 (C) and 21 (B ii) i didn't understand the explanations for the 2 isomers

http://www.edexcel.com/migrationdocuments/QP GCE Curriculum 2000/June 2012 - QP/6CH02_01_que_20120523.pdf
Jun 2012 Q16

Jan 2012:
question 17:
D, the molecular ion peak is the same because they have the same RFM

question 20c)
KI reacts with Chlorine and since chlorine is a better oxidising agent than Iodine, it displaces the iodide ion out of its salt causing it to be oxidised to iodine. The solution at this stage turns brown. As the thiosulfate ions reduce the iodine to iodide, the color fades and eventually it becomes pale yellow. The transition from pale yellow to colorless would be too "settled", so they wouldnt know exactly when the end point is reached. They use starch (which is the indicator for iodine), which turns blue to get a more observable color change
so,
from pale yellow
blue-black
colorless

21bii) Just read your notes or the book for the reaction mechanisms. The fact that they are different types of halogenoalkanes (primary and tertiary) means that they undergo nucleophilic substitution reactions through different mechanisms

June 2012:
16)hmm.. i think it's A
They are non-flammable since they were used in aerosols and as blowing agents and what not. i think they dont support combustion because of the strong C-F bonds but i am not sure
B+C+D are correct so it has to be A

 

[IsraJ]

plzz help me with some questions i know the answer (from the mark scheme) but need to know the explanation and reason plzzz

http://www.edexcel.com/migrationdocuments/QP GCE Curriculum 2000/January 2012 - QP/6CH02_01_que_20120307.pdf
Jan 2012 Q17 and Q20 (C) and 21 (B ii) i didn't understand the explanations for the 2 isomers

http://www.edexcel.com/migrationdocuments/QP GCE Curriculum 2000/June 2012 - QP/6CH02_01_que_20120523.pdf
Jun 2012 Q16

Jan 2012:
Q17- The answer is D since they have the same molecular mass of 58 and the statement in D says that their molecular ion peaks are different while they arent
Q20 C- iodine dissolved in water is yellow but when it is added to starch, it turns blue black. At the end point, the colour is then, colourless.
Q21 Bii- you need to know the mechanism for this. ( i have attached it) Just know that primary carbocations and tertiary carbocations follow different mechanisms since tertiary carbocations are stable while primary aren't. Please learn the steps in the uploaded file.
Jun 2012 Q 16- it's A and this cannot be explained cuz this is a property of CFCs and you need to know this. You are supposed to learn the properties of CFCs.

 

[aligatorviper]

guyzz just wanna ask if i m asked to draw shape of molecules such as octahedral, will i hav to draw it in 3d or just simple lines in the plane. n second to join all the corner making pyramid stuff or just a simple diagram of the bonds???????plz tel im little confused coz i hav seen no example in markscheme etc..
also abt the colors of iodine n iodide ion in oll the solvents..