Chemistry P4| A2 only

[zain tariq]

guys plz guide me!I have prepapred all the pastpapers and everything from the book!how do i revise the course now,like should i only study the applicatoins booklet and the revise my notes plus do the As organic aswell?

 

[smzimran]

guys plz guide me!I have prepapred all the pastpapers and everything from the book!how do i revise the course now,like should i only study the applicatoins booklet and the revise my notes plus do the As organic aswell?

Exactly!

 

[histephenson007]

histephenson007 said: ↑

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s10_qp_42.pdf

3.d)i) dafuq?? we should find out the answers by trial and error method or what/??? also include ii) plz​

Is everyone sure that the only way to solve this is by trial and error method?! Does anyone have other ideas?
​

 

[zain tariq]

ok...in may june 2011 in Q3 part c ms says that BR2 is produced at anode instead of O2 by electrolysis of aqueos MgBr2!is this correct

 

[hendrixgirl]

hey you guys .. OCtober november 2007 .. question number 4) b) ii)

its supposed to be a simple enthalpy question ... can someone help me on the PbCl2 + Cl2 ----> PbCl4 ??
why didnt they include +244kJmol-1 for the Cl2??

 

[zain tariq]

cause enthalpy of formation of elements is 0

 

[hendrixgirl]

cause enthalpy of formation of elements is 0

what does that mean?

 

[princesskt]

what does that mean?

formation is products -reactants
for an element product have same energy as reactant so it is zero.............

 

[zain tariq]

smzimran bro plz answer my question few posts above

 

[hendrixgirl]

formation is products -reactants
for an element product have same energy as reactant so it is zero.............

so why is it different in CCl2 + Cl2 ----> CCl4 ???
why dyu include Cl2 in this?

 

[zain tariq]

cause here u are using bond energy data not formation data to solve answer

 

[hendrixgirl]

cause here u are using bond energy data not formation data to solve answer

oh ok .. thanks. :/

 

[hassam]

So the answer must be written in the book - which book is that btw?

coursebook cIE....

 

[histephenson007]

ok...in may june 2011 in Q3 part c ms says that BR2 is produced at anode instead of O2 by electrolysis of aqueos MgBr2!is this correct

yes, you can check with Standard electrode potentials if you want. Usually, instead of O2, halogens (except Flourine) Cl2, Br2, and I2 get released when electrolysis takes place in aqueous solutions.

 

[zain tariq]

I dont think so!the reduction potential of br2 is more positive than that of forming o2 so it should be more difficult to oxidise

 

[princesskt]

I dont think so!the reduction potential of br2 is more positive than that of forming o2 so it should be more difficult to oxidise

i agree wit h u i also think o2 should be the ans..........as o2 is easier to get oxidised...............

 

[musa Khan]

http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_s11_qp_43.pdf

hey guys, how do you do the question you guys are discussing? question number 3 c?
how do you look at the electrode potentials and decide whats get oxidised and what not?

 

[musa Khan]

also what values do you look at? please help I'm soo failing this exam i don't know anything and smz imran thanks for solving my question broo

 

[musa Khan]

actually I figured it out myself hehe thanks anyways

 

[musa Khan]

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?