Chemistry P4| A2 only

[hassam]

Explain why the enzyme lysozyme, which consists of 129 amino acid residues, requires
a triplet code of 393 bases..
ms says 129*3=387 this leaves 3 bases for start codn and 3 for stop.............bt the problem here is...that ok stop codon ....there is no amino acid corresponding to it....bt for start codon there is methionine .....isnt it?

 

[elitessg]

How are supposed to do 3.a) ??
Are we supposed to know how d-orbitals look like????????

we do that they are double dumble shaped and 5 types of d orbitals are dxy dzy dxz dz(square) dx(square)y(square)

 

[hassam]

To improve soil ‘quality’ by precipitating clays???? zishi

 

[Zishi]

To improve soil ‘quality’ by precipitating clays???? zishi

I'm not fully sure, but I think that it means that Ca(OH)2 can be used to precipitate some metal ions, which would otherwise be not good for the soil.

 

[smartangel]

how is Cu a transition element..it doesnt have an incomplete d orbital..?

 

[Paradoxical]

how is Cu a transition element..it doesnt have an incomplete d orbital..?

A transition element is one that forms an ION with an incomplete d-orbital. So Cu2+ is [Ar]3d9

 

[smartangel]

*contrast, qualitatively, the melting point, density, atomic radius, ionic radius, first ionisation energy and conductivity
of the transition elements with those of calcium as a typical s-block element..i went through roger norris for this..it only states the difference between the two. do we need to know WHY there is a difference in these properties of s block n d block elements?

 

[sophiaaa]

Salam to All!
A request to all A2 students preparing for chem p4 on 25th may:
Use this thread to post your doubts!

hey plz.post some notes on nmr spectrosccopy...

 

[kirashinagami]

Easy question here - ligand

http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_s10_ms_41.pdf

No 2 part b .. How can we know grey green ppt is Ni(OH)2 ,, I mean we are not taught so!!

 

[desmondyap93]

Hey guys I need your help...
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s10_qp_41.pdf
Question 5 (iii) and (iv)
May I know why the answers for both sub questions are "more negative"? I don't know the reason behind ><
For (iv), why the answer is "E remains the same".
Thanks in advanced!

 

[kirashinagami]

Hey guys I need your help...
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s10_qp_41.pdf
Question 5 (iii) and (iv)
May I know why the answers for both sub questions are "more negative"? I don't know the reason behind ><
For (iv), why the answer is "E remains the same".
Thanks in advanced!

Here first of all see the reactions.
If OH is increased, the reaction in cathode will favours to the left due to increasing number of reactants, the 2e on the right hand side will increase also.. So become more negative.

Same applies for anode or right hand electrode, increasing the OH conc will move the reaction towards the left and electrons are produced more..

For the fourth part, look at both equations, the above got 2 OH and below got 4 OH, multiply the above equation by 2 and so the no of electrons on both sides are the same, so it remains the same.

 

[desmondyap93]

Here first of all see the reactions.
If OH is increased, the reaction in cathode will favours to the left due to increasing number of reactants, the 2e on the right hand side will increase also.. So become more negative.

Same applies for anode or right hand electrode, increasing the OH conc will move the reaction towards the left and electrons are produced more..

For the fourth part, look at both equations, the above got 2 OH and below got 4 OH, multiply the above equation by 2 and so the no of electrons on both sides are the same, so it remains the same.

Thanks a lot!!!!!!!!!!!!!!!!!!!!!!!

 

[smartangel]

http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_w09_qp_41.pdf
Q3 b..

 

[Waleed Asim]

(iv) In sunlight the complex decomposes into potassium ethanedioate, iron(II)
ethanedioate and carbon dioxide.
Use oxidation numbers to help you balance the following equation for this
decomposition.
K3Fe(C2O4)3 -------> ...........K2C2O4 + ......FeC2O4 + ......CO2

 

[musa Khan]

http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_w11_qp_43.pdf

question number 3 e iv
Please someone solve it, it's about pka

 

[Peppers]

why can't acyl chlorides form hydrogen bonds?

 

[Sky8]

which is the correct graph for enzyme reaction ?

 

[larina]

which is the correct graph for enzyme reaction ? View attachment 10460

both.
if its a one-step reaction then the first one is correct
if its a 2 step reaction, the 2nd one is correct

 

[larina]

(iv) In sunlight the complex decomposes into potassium ethanedioate, iron(II)
ethanedioate and carbon dioxide.
Use oxidation numbers to help you balance the following equation for this
decomposition.
K3Fe(C2O4)3 -------> ...........K2C2O4 + ......FeC2O4 + ......CO2

just balance it in a normal way.

 

[musa Khan]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w11_qp_43.pdf


can someone PLEASE answer question number 3 e iv and also question number 7 C ii? how is the answer bromine? how do you work it out? actually can someone please explain all of question number 7? my notes on nmr are pretty bad this will also help everyone get a good overview of the nmr chapter

please helpp... can't move on until I figure these two out! your help will be much appreciated