Problematic questions.........

[danfriday92]

Guys, please help me! I problem with question 2, 6, 7, 13, 15, 22, 25, 29, paper 11 m/j 2010

Thanks in advance.......

 

[hassam]

which subject

 

[danfriday92]

Arh....chemistry. Sorry I forgot to include that...

 

[workinghard]

here goes bro hope it helps
2. u c across da period I.E increases and down da group it decreases since nuclear pull increases across d aperiod n decreases down da group...
so ans is A Fr is least endothermic and than Ra because it s later in period n highest is Rn cuz it is latest in group and highest in period!
6.NH4NO3 --> N2O + H2O
N in NH4 hs oxdation state of -3 it is lifted to +1 in N20 so da change is +4
N in NO3 has oxidation state of +5 and it is lowered to +1 in N2O so da change is of -4 and tha ans is D
7. temp change always increases rate of both side of rections since there are more frequent effective collisions. yeah i matters wheher da reac is endo or exo but here it increses bth rates so A
13. since dere is no change in oxidation state of Na or any other it can't be oxidation or reduction iit acts as plain acid therefore
H2SO4 + NaCl --> NaHSO4 + HCl
15 N2 + 3H2 --> 2NH3 (its a equilibria reac)
sinc gases r involved pressure counts increasing it ll move the process towards the side with fewer mol ie NH3 and since reac is exo decresing the temp increases the reaction so A
22 honestly speaking i dont no or never bothered 2 try writing it and solving it just memorized da ans which is H2SO4!!
25 it is C NaOh ll reverse ester formation forming propanol and sodium ethanoate
29 it ll be hard 2 xplain without drawing structures but i believe the ans is butan-2-ol
did this helped??????????? :?: :?:

 

[WellWIshER]

GUYS!

can someone explain me chemistry ppr 4 J09 Q2!???

 

[workinghard]

GUYS!

can someone explain me chemistry ppr 4 J09 Q2!???

wait up a sec i'll look it up n try!!!!

 

[workinghard]

so yeah da 1st part is pretty simply HCl and Hbr ll b formed HCl has misty fumes and Hbr has Brownish tint to the fumes (bcuz of bromine)
part b u quote the relative values CL/CL- 1.36 & Br/Br-1.07
according to the Cl- ion is more easily made since thee E0 value is more +ive and hence it is atronger oxidizing agent and the reaction of it is more vigorous
it can accept e's more readily!

(c) u have to quote a reductant with value less than dat of Br/Br- ie 1.07 ao that wen v subtract da E0 value of reductant to check da feasibilty of reaction it is +ive n reaction is suitable
select any thin 4m wide list its alllowe!
Helped???????????????

 

[WellWIshER]

dude y are da values of cl and br NEGATIVE arent they positive ??? wont they be reduced!!!

wt abt da equation!!!!!!

 

[workinghard]

dey r most definitely +ive
i wz tryin 2 stres bout da fact dat its Chloride -ive ion!!!!!!! Cl-
get it?
Zn2+ + 2e' --> Zn -.76

eq is
Zn + Br2 --> Zn2+ + Br- (1.07 - (- .76)) = 1.83V
if i'm not wrong!!!!!!!!!!!!!
helped now????

 

[WellWIshER]

i dont get da reaction between nacl nabr with h2so4

using E values its not possible ryt???

y did u state negative values for cl and br ions????

please clarify
thanx 4 da effort

 

[WellWIshER]

btw i am talking abt da 1st part

i got da last part with br

 

[workinghard]

its possible usin Eo values
c formation of CL- ion from Cl atom has +ive E0 value indicatin feasiblitiy wen Nacl reacts with H2So4 it forms NaHSO4 or Na2SO4 ie it displaces H and H combines with Cl forming HCl or HBR and the +ive values of ion formation of Cl- and Br_ supports this hypothesis....
shd i rite down the symbolic equations
did this help???????????/

 

[danfriday92]

Thanks a lot, you've been workinghard each day......
Supposely the answer for 25 is B, but its ok. Anyway, can someone please help me with question no. 29?? I can only find 2 different products........drawings will be pretty much appreciated.

Thanks in advance

 

[workinghard]

@danfriday92
i no its B! wat did i rite???????????
u wr able 2 mak 2 products
da third product is the cis or trans isomer of one of the two products u already made dependin on wat u did make!

 

[workinghard]

oh i rote C ma bad its B!

 

[WellWIshER]

its possible usin Eo values
c formation of CL- ion from Cl atom has +ive E0 value indicatin feasiblitiy wen Nacl reacts with H2So4 it forms NaHSO4 or Na2SO4 ie it displaces H and H combines with Cl forming HCl or HBR and the +ive values of ion formation of Cl- and Br_ supports this hypothesis....
shd i rite down the symbolic equations
did this help???????????/

how is it possible?? 4rm which part of da syllabus is dis i mean da eq between h2so4 and nacl???????

and how is da reaction possible

da E value 4 cl is + where as 4 acid is zero?????

 

[workinghard]

i really m tryin 2 xplain
n failin badly
look 4gt bout the E0 value and try 2 do the eq as u'll do it in o or as level
u can rite it rite
den look at Eo values
the positive Eo value indicates that it is quite possible 2 make a Cl- ion 4m Cl atom
and then look back at the equation
u ll c presence of Cl- ions ..... ie reaction is feasible
i dont no wat value u r referin 2 as 0 but even if it is 0 the net value is +ive and so the reaction is possible
geddit?

 

[WellWIshER]

thank you 4 trying harder ur not only working hard but also xplaining hard!

i know feel like banging my head against the walll

aftr all dis tyme i am nt getting dis q!!

DONT WE HAVE TO USE DA E VALUE OF SO2??

WHERE IS DA REACTION B/W NACL AND ACID MENTION IN DA SYLL

EVEN IF I APPLY MY CHEM I DONT GET IT??

Y R DA EQ 4 NABR AND NACL DIFFERENT??

 

[workinghard]

kkkkkkkkkkkkk
well thnx
i'm pretty sure i'll hv 2 change ma user name soon !
afteral i m not working THAT hard!
no i dont think u need 2 use E0 value of SO2
i dont no ... i really dont no where it is written in syl
c i hardly open it unless i hv 2 absolutely do so
dont apply ur chem it ll oooonly confuse u
thnk of it as a simple reaction dat ull solve in olevel or as like i sugested!
oh oh oh!!!!!!!!!!!!
sorry!
i hv bin goin about it da wrong way
no wonder i'm confuisng u
sorry !
u r half rite n e is half rite
now i get it u r talkiin bout the formation of br
its in the chapter of halogens in A2
the thing is dat H2SO4 is an oxidizin agent
since the value of Br/Br- is negative realtive to CL/CL- it is more easily oxidized
in other words Cl/CL- is 1.36 so there is a gr8r chance of ion formin rather tha n cl2 gas
these eq r part of syllabus
in I the reaction also resulds in formation of I solid
shd i rite all the eq down 4 future reference????
sorry again i misuderstood ur ques!

 

[WellWIshER]

THANK GOD we r in rite terms now...


but see

in order to react h2so4 with nabr we should have a more +ve value 4 h2s04 as it will oxidize nabr or nacl???

so how is da reaciton possible?