Chemistry P4| A2 only

[shyqueen]

june 2007 ques4 plz sumbody explain da shape ov d orbital in dis one? i mean it says draw one dprbital in each ov two groups? i dunt get da ques :S

 

[hendrixgirl]

june 2007 ques4 plz sumbody explain da shape ov d orbital in dis one? i mean it says draw one dprbital in each ov two groups? i dunt get da ques :S

draw dx^2y^2 and dz^2 orbitals

 

[shyqueen]

thnks n can yuu plzz explain da nxt part in which it says which has higher energy 2 orbital group or 3 orbital?

 

[musa Khan]

guys, will ch3cooh give a positive iodoform test ? cause well we still have ch3 and C double bond O.. so shouldn't it? :/

 

[larina]

guys, will ch3cooh give a positive iodoform test ? cause well we still have ch3 and C double bond O.. so shouldn't it? :/

acids never give a positive iodoform test!

 

[hendrixgirl]

thnks n can yuu plzz explain da nxt part in which it says which has higher energy 2 orbital group or 3 orbital?

those electrons in those particular orbiitals are repelled .. this is the 2 goup one .. so they have higher energy

 

[larina]

Can someone please tell me how to do Nov 2011, p43, question 3(e)(iv)!!
http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_w11_qp_43.pdf
im using the equation pH= pKa + log [base/acid] and im gettingg 4.36...

 

[Lion Power]

Why is phenol acidic than water........ and ethanol the least acidic .....( explain in trems of the OH bond )

 

[musa Khan]

http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_s10_qp_41.pdf

in question number 5, does the more negative electrode potential always occurs the cathode? that is before we switch it's sign around? like for e.g in the question the more negative of the equations is occuring on the cathode.. so is this true for all cases? also, what's the logic behind the answer to part iii?

 

[musa Khan]

Lion Power because in phenol the lone pair of oxygen is delocalised over the ring system thus the charge magnitude is diminished, lesser charge magnitude on the oxygen atom means more stable anion formed and this increased stability of anion is attributed to the high acidity of phenol whereas using the reverse argument, presence of an electron releasing methyl group in ethanol means the anion formed is less stable and thus the acidity is decreased.

 

[smzimran]

smzimran bro, the ph= pka + log(salt/acid) is this like a proper formula?
Also, do we take the MOLES of salt and the acid or the CONCENTRATION?

Yes it is the proper formula

We normally take concentration but in this case since volume of both salt and acid are same, they will cancel out so thats why just ratio of moles is left!

 

[musa Khan]

smzimran thank you brother, can you explain to me the logic behind question number 5 part iii? marking scheme says that many people got it wrong so it might also help out others! http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_s10_qp_41.pdf

 

[smzimran]

smzimran thank you brother, can you explain to me the logic behind question number 5 part iii? marking scheme says that many people got it wrong so it might also help out others! http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s10_qp_41.pdf

Not now, kinda busy with maths s1, have paper in a few hours!

 

[Zishi]

coursebook cIE....

Page number?

 

[Mobeen]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s08_qp_4http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s08_ms_4.pdf.pdf
Q b(iii) and (c) urgent plz...

 

[musa Khan]

smzimran actually it's fine.. scrolled back, someone had asked the same question, good luck for your paper

 

[Mobeen]

http://www.xtremepapers.com/papers/...d AS Level/Chemistry (9701)/9701_w08_qp_4.pdf http://www.xtremepapers.com/papers/...d AS Level/Chemistry (9701)/9701_w08_ms_4.pdf Q6(b) (c) (d) people help me out with this and suggest me how to do these kind of qs...?

 

[Pratik.Dhakal]

smzimran thank you brother, can you explain to me the logic behind question number 5 part iii? marking scheme says that many people got it wrong so it might also help out others! http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s10_qp_41.pdf

now just add PbSO4 to the overall reaction you found above, before adding PbSO4 you had Pb2+ formed so now after adding PbSO4 the SO42- combines with Pb2+ and forms 2PbSO4

 

[DragonCub]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w08_qp_4.pdf http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w08_ms_4.pdf Q6(b) (c) (d) people help me out with this and suggest me how to do these kind of qs...?

(b) Phenylamine, like phenol, can be involved in electrophilic substitution with bromine. The product, 2,4,6-tribromo-phenylamine, is also a white precipitate. So the test can be carried out using bromine water. Phenylamine reacts to decolourise the solution and form a white ppt. while amino-cyclohexane does no reaction.
(c) Acyl chlorides can react with alcohol to form easter while releasing HCl molecules. So adding alcohol (such as ethanol) is a good way. Propanoyl chloride reacts to give out HCl gas and easter while 1-chloropropane undergoes no reaction.
(d) Propaneamide is neutral since the amide bond is neither acidic nor basic. Propaneamine shows some basic features due to the pone pair on nitrogen. So simply testing their pH values can show the diffrence.

 

[musa Khan]

guys, can you confirm whether I've got my facts right? okay so in the electrochemical cell, the electrode at the left hand side is essentially a cathode and the equation which involves a more negative electrode potential value goes here but instead of reduction oxidation takes place here and the electrons are released while on the right hand side we have an anode and recuction takes place here and the more positive electrode potential value comes here (less reactive equation) and the electrons are used up?