Chemistry paper 31 (NEW)

[AhmedMans]

nop
it forms a ppt

Do I HAVE to write precipitate?
I made the first one : Grey colour
Second one: Brown colour

????

it doesnt form a ppt..so grey colour and brown colour i think wud b the safest ans... :wink:

Great!

 

[AhmedMans]

One thing, I forgot to put the:

---( )---n after I did the nylon drawing, how much do I lose? 1 or 2 marks? And I did them with boxes too....

 

[Ramosk95]

i didn't do boxes but you should also write +h2o bcz its a condensation polymerisation

 

[Ramosk95]

The selenium one was that it is acting as a reducing agent because it removes the Oxygen from the what ever the reaction was. I forgot it.

i remembered a qsn in the past papers that says what type of reagent ................ so it would be an acid or a base not a reducing or an oxidising agent so i wrote a base because it is a proton acceptor but i think i'm talking about a different qsn (don't remember)

 

[AStarHunter]

i didn't do boxes but you should also write +h2o bcz its a condensation polymerisation

oh man ! What did the qs say ? Cause i didn`t write h2o !

 

[Ramosk95]

i didn't do boxes but you should also write +h2o bcz its a condensation polymerisation

oh man ! What did the qs say ? Cause i didn`t write h2o !

draw the structural formula of the polymer that is resulted from the following monomers but i think its not essential

 

[AhmedMans]

One thing, I forgot to put the:

---( )---n after I did the nylon drawing, how much do I lose? 1 or 2 marks? And I did them with boxes too....

 

[Ramosk95]

i think with boxes or without it would be the same but not sure!

 

[LimeReem]

How to find out the grade boundaries for 2010?

 

[Ramosk95]

How to find out the grade boundaries for 2010?

http://www.xtremepapers.me/CIE/Cambridg ... w10_gt.pdf

 

[nightwalker221]

Grey colour of what
you can't just only write that.

 

[Ramosk95]

a qsn guys i wrote the polymer -----(oc (ch2)4conh (ch2)6nh)----n is it the same as with boxes or what??

 

[NOOB12345]

Can someone tell me the answer to

1) Which of the acid reaction is the redox reaction and the reason? (Li + HI), (Zinc Carbonate + HI) or (the one with MgO)
2) Which carboxylic acid forms when acidified potassium manganate react with Butanol? and its structural formula?

For your info, I choose:

1) One with MgO, as oxygen is involved (the explanation probably wrong)
2) Butanoic Acid, CH3CH2CH2COOH

Can someone confirm?

 

[AhmedMans]

Can someone tell me the answer to

1) Which of the acid reaction is the redox reaction and the reason? (Li + HI), (Zinc Carbonate + HI) or (the one with MgO)
2) Which carboxylic acid forms when acidified potassium manganate react with Butanol? and its structural formula?

For your info, I choose:

1) One with MgO, as oxygen is involved (the explanation probably wrong)
2) Butanoic Acid, CH3CH2CH2COOH

Can someone confirm?

1) I chose Lithium one since Lithium loses an electron and Hydrogen gains it.
2) I made it just like you!

 

[Adahshan]

Lithium is the write one and second one i did same.

 

[nightwalker221]

It was the 3rd reaction right, because lithium was reduced as it gained hydrogen and etc

 

[xIshtar]

Uhmm, I put the redox one was the second carbonate reaction. As zinc was reduced to zinc iodide, and the H ion was oxidised to water..

 

[xIshtar]

But for the second one I wrote the same thing..


I wrote for the chlorine one, a colour change from colourless to black/dark brown, and a colour change to yellowy brown.

I wrote that the Selium was the reductant, I though about writing a base, but I've only ever seen a question asking you to describe that worth 2 marks, and this one was 3, meaning 3 things were needed, so I chose that it was a reductant, as it was oxidised, and the other one was reduced, as it went from neutral charge to -1.

 

[xIshtar]

And for the hard moles one, I wrote that the molar ratio between the metals and the hydrogen was the same with A and C, but with B it had a higher ratio, meaning a higher amount of moles and thus a large volume was produced

 

[NOOB12345]

I wrote for question 7b, that metal B produce more hydrogen because:

Aluminium has valency of 3 and Chlorine of 1, the formula for Aluminium Chloride is AlCl3, where as for the other 2 metals is MgCl2 and ZnCl2. Therefore 1 Mole of Aluminium will react with more moles of HCl than Zinc and Magnesium, hence producing more hydrogen.

and I wrote the same/similar for 7a where you have to identify metal and explain. Don't know if this will score me the explanation for why Metal B is Aluminium. (I heard many people explained metal B using reaction rate and oxide layer) I hope mine is an alternative answer... And btw why is 7a, the identification and explanation of metals only 5 marks? (I thought it would be 3 pairs of marks)

and what did you write for the explanation for the 2 other metals?