Edexcel CHEMISTRY DOUBTS!!!!

[Amelia]

Lia Sorry but I got two more 

Q 18]b)ii)...19]c)

Thx

I can answer Q18bii) - Isomerism in alkenes (Cis & Trans) arises due to double bond between the carbon atom containing one sigma and one pie bond. Presence of pie bonds prevents free rotation of the atoms or groups of atoms attached to the Carbon containing double bonds.
Hex-1-ene the bonds are present between the 1st and 2nd carbon atom, in Hex-2-ene the bonds are present between the 2nd and 3rd Carbon atom.

[The Golden Girl =D]

girl thanks I finally get it :*

[The Golden Girl =D]

Can anyone do 19 ?!

[Deadly_king]

Can anyone do 19 ?!

I believe you were able to do part (a) and (b) yourself.

19.(c) Higher atom economy : Method using ethene.

This is because during this reaction no other products which would lead to loss of atoms are formed. The reaction with ethane however will also form white vapour of HCl which is lost to the surroundings. In other words there is loss of one atom of chlorine and one hydrogen atom.

Higher percentage yield : Method using ethene again.

This is because HCl which is used as reagent in this process is a polar molecule which will immediately cause the reaction to take place. The reaction involving ethane however is free radical reaction and will depend on the probability that the Cl-Cl bond (Cl₂ is reagent) is broken.

Moreover if you find the Mr of ethane and ethene, that of ethane is greater by 2 units. So the theoretical yield will be greater for ethene.

Theoretical yield = Mass of product / Mass of reactant x 100

However, here we are asked about the % yield which is give by : actual yield / theoretical yield x 100.

But we have not been given the actual yield. So I can't say this for sure.

NOTE : For the yield, am not sure about it. This is my theory. So I'll recommend to consult your teacher.

[The Golden Girl =D]

For the yield part the first paragraph are u sure of that? If u r could u plz explain it again . Thx

[blackberry]

need urgent help guys!!!

(hodder education)george facer chem textbook's definiton of a system-term used to represent the reaction mixture,including any solvent and the reaction vessel.
(pearson company)chem student hanbook's definiton of a system-a chemical reaction i.e reactants and products of a reaction are the system

which one is the right definition???!!

[Master_Key]

need urgent help guys!!!

(hodder education)george facer chem textbook's definiton of a system-term used to represent the reaction mixture,including any solvent and the reaction vessel.
(pearson company)chem student hanbook's definiton of a system-a chemical reaction i.e reactants and products of a reaction are the system

which one is the right definition???!!

If you will search the third textbook you will get the third definition too.

So it is on your teacher and you to take which one is correct.

Basically both have the same content, but the words differ.

[blackberry]

yaa i kant really get nuther txtbuk at this moment!

ooo by the way the definitons are almost the same but its the vessel part in which the reaction takes place that both textbuks giv different definitions. one says that the vessel is part of the surroundings and the other says its part of the system. only one can be right but its hard to know which one. i evn checked on the internet and they give different definitions.the teacher just follows the textbook that we use in school so she wudnt know beyond that...... i really need to know what the edexcel people will accept in the exam......

[Deadly_king]

For the yield part the first paragraph are u sure of that? If u r could u plz explain it again . Thx

Yeah...............am pretty sure about it.

HCl as you now is a polar molecule due to the presence of an electronegative atom; chlorine. Hence it will easily break to give H and Cl atom so that they undergo any particular reaction.

As for the reagent in the 2nd method : Chlorine, it is not polar since both electronegative Cl atoms cancel out each other. Hence for the Cl-Cl bond to break, U.V light is needed. Even when available, there it is probabilistic that this bond breaks. Hence it will take more time.

But now that i think of it, rate of reaction will surely be faster but yield would be the same. So I think this is not the appropriate answer.

[The Golden Girl =D]

Yeah...............am pretty sure about it.

HCl as you now is a polar molecule due to the presence of an electronegative atom; chlorine. Hence it will easily break to give H and Cl atom so that they undergo any particular reaction.

As for the reagent in the 2nd method : Chlorine, it is not polar since both electronegative Cl atoms cancel out each other. Hence for the Cl-Cl bond to break, U.V light is needed. Even when available, there it is probabilistic that this bond breaks. Hence it will take more time.

But now that i think of it, rate of reaction will surely be faster but yield would be the same. So I think this is not the appropriate answer.

The Answer that my teacher gave me was as follows :

No other products with different substitutions .

It means that there are NO side products hence the Percentage yield is higher

Thanks By the way

[Deadly_king]

The Answer that my teacher gave me was as follows :

No other products with different substitutions .

It means that there are NO side products hence the Percentage yield is higher

Thanks By the way

Aah.................I get it now. I used the same explanation for the first part. So I did not heed it for the second.

Anytime GG 

[The Golden Girl =D]

I got several doubts ,I've checked the Answer in the MS but I don't Understand why is it so  

Explain to me how to get to the Answer ,ok ?

June 2010 Unit 1

Qs 4]a) and d) ....5] ..9] I don't get y should we mulitply it by 2/3   ..... 10]

Answers are ;  Q4] a) B and d) A ...5] B ......9] C ..... and finally 10] C

Thanks In Advance

[elemis]

On it.

[elemis]

Question 4

[elemis]

Question 4 (b)

Since we know that Neon is element C simply count backwards 4 to find that Carbon is actually element A.

Therefore answer is A.