Chemistery P22 (As Strustured questions)

[Frooty]

hey guys share ur answers of the 1st question here..(after 24 hr barrier) i lost 9 marks from there i guess :/
remaining paper was hell easy and i guess 2 of the questions were from past papers!!

 

[eva 21]

i think I'm gonna loos 4 marks from question 1...
the last part of it had me scratching my head until i was convinced that i had suddenly been invaded with dandruff... :shock:
:ugeek:

ah well...
question number 4 made my jaw drop...
WHAT WAS THAT???!!!

 

[RatJumper]

question one raped haha i think i lost like 6 mrks

 

[jerry]

same exactly.....even i think i lost lyk more than 6 marks!!!!!!
you guyz cmon,i guess its past 24hrs....what molecular formula did u get for the first qs???

 

[jerry]

and what was question 4 about?cnt rmr!

 

[Djoyakim]

i found the paper very easy..question 1 is usually a multiple choice question.. but i guess p4 will be very difficult.. practical was ok , p2 ok , p5 good.. now they are going to burn us alive on p4 and p1

 

[Edifier]

What were the gases you guys identified in Question 1?
i wrote this for each part
(i) O2
(ii) CO2
(iii) 10 cm3
(iv) 10 cm3

And i still think all of these are wrong. But still Fingers Crossed. =p

And i made a really wild guess on the Molecular formula. I just wrote it C4H8. I did so some sort of calculation for it that wouldn't even count i think since this was just a guess. =p
I dont like leaving the questions blank so i just write what come's to my mind. =p

Rest of the paper wasn't that hard. Although i do think that i did mess it up a little bit. But InshAllah i'll be hoping for an A if i do good in Paper 1. =)

 

[jerry]

omg really!
srsly i wrote the exact same answers in the same sequence,wrote O2,C02,1OCM3,10CM3!
Are there any chances for this question to be right??:S:Sanyone?

and i ddnt get the molecular formula.....my mole ratio of the emperical formula was cuming CH3
:S:S:S:S:S:S:S
this is how i end it up...ddnt write the molecular formula though!
plz anyone....what was your answer??

plus HOW DID U BALANCE THE EQUATION?I CUDNT DO THT:'(

i'

 

[jerry]

the equation was....

CxHy + (x+y/4)O2-->...CO2 + ...H2O

how to balance that?

 

[mathmaster]

CxHy + (x+y/4)O2-->xCO2 +y H2O

 

[mathmaster]

wait!how come you guyz wrote O2 as a combustion product?i dint do that..aaaahh..i figured the combustion products were co2 and h2o.the gas was water vapour.the physical state symbol for the combustion products are both gas.am i wrong?

 

[jerry]

Well i dont think it was a combustion product...it was the amount remaining,dun really remember the question sequence..but do remember the answers!combustion product was the second one,co2,think so....ryt?

 

[blue]

@mathmaster...
lets not forget tht the hydrocarbon cud have been an alkene!!
then the equation becomes this
CxHy + (x+y/4)O2-->xCO2 +x H2O


also the combustion product was co2 ..and the volumes were
10 and 20
not 10 and 10
then only the final molecular formula came out as
c2h4
thanku

 

[eva 21]

our teacher taught us that equation, and i remember it was
xCO2 and (y/2)H2O
(i'm positive about that..)

i dont remember the sequence tho... :geek:
(mayb i will if sumone cud repeat the questions...)

i guessed that the molecular formula was CH4...
cuz the ratio of oxygen:co2 was 2:1...
(i'm really scared about that one...) :?

 

[eva 21]

@mathmaster...
lets not forget tht the hydrocarbon cud have been an alkene!!
then the equation becomes this
CxHy + (x+y/4)O2-->xCO2 +x H2O


also the combustion product was co2 ..and the volumes were
10 and 20
not 10 and 10
then only the final molecular formula came out as
c2h4
thanku

yaaaaaaaaaay!
my volumes also came as 20 (for O2) and 10 (for CO2).
(and i'm pretty sure abt that...)
(i think...)

 

[Djoyakim]

o2 and co2 are good. 10cm3 for o2 was used up and 10 cm3 of co2 was produced. i got the hydrocarbon as methane CH4.. and u guys ???? hey it is said in the question that it is an unsaturated hydrocarbon..

 

[eva 21]

o2 and co2 are good. 10cm3 for o2 was used up and 10 cm3 of co2 was produced. i got the hydrocarbon as methane CH4.. and u guys ???? hey it is said in the question that it is an unsaturated hydrocarbon..

yeah! so since its unsaturated... it CANT b an alkene.
but how'd u get the 10 and 10 values?
i got 10 and 20...
hmmmmmmmmmm...
:ugeek:

 

[JK_1995_15]

Guys you got the equation wrong it is:

CxHy + (x+y/4)O2 - - - > xCO2 + y/2 H2O BECAuse if you wanna get y you need y/2 because you have h2o that two there is the answer

 

[JK_1995_15]

oh also .... The gas that reacted with KOH is Co2 10 cm of it The gas that was left was the excess of 02 that did not react i guess it was can t remeber the volume i GOT C2H6 as the hydrocarbon the rest of the test easy any opinions?

 

[JK_1995_15]

Guys you got the equation wrong it is:

CxHy + (x+y/4)O2 - - - > xCO2 + y/2 H2O BECAuse if you wanna get y you need y/2 because you have h2o that two there is the answer
oh also .... The gas that reacted with KOH is Co2 10 cm of it The gas that was left was the excess of 02 that did not react i guess it was can t remeber the volume i GOT C2H6 as the hydrocarbon the rest of the test easy any opinions?