Chemistery P22 (As Strustured questions)

[mathmaster]

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...) :?

do u know how u derived tht value??y/2??well are guys sure its o2 and not h2o??i am done for

 

[mathmaster]

alrite!KOH is compound that readily dissolves exothermically in water .it is a CO2 and H2O absorbent..it absorbed water and co2 from the air when placed in..which means the gas we have left is excess o2..

 

[SAN]

how in the world did u guys find the paper easy???
it was damn difficult....
the last Q: one mark lost there....thn i guess there was no solvent for the first reaction in Q4..
thn i couldnt gt the molecular formula for Q 1or the heat absorbed Q.......
n wht was the equation for C2Cl2F2 ??
shoot...
i guess ill have to re-re-appear....

 

[loly23]

omg!!
how could u find this paper difficult?
the first question was so easy,it's what ive been doing last year at the beginning!
well 4 the eqn it is xCO2 and (y/2)H20
then the volume of O2 used up was 10
the gas absorbed by KOH is Co2,volume 30
then the molecular formula is CH4

paper of the yr!!!!

 

[jerry]

cud u plz explain HOW did u derive the first equation in question 1 to get y/2???
and how did u get CH4???

 

[amirazi]

CxHy+(x+y/4)O2=xCO2+y/2H20
WELL GUYS I THKS ZAT ZE RITE EQN
I LOST MANY MARKS ON ZAT PAPER
ON QUEST NO4
IT ASKED 4 ZE SOLVENT I WAS PANICK
AND WRITE ZE PRODUCT
P5 WAS HORRIBLE WIZ ZE PLANNING
GUDLUCK 4 ZE REMAINING PAPER

 

[doga]

molecular formula CH4,..........and ya though i did find the gas which is co2 but rest harash me

 

[SAN]

@loly23:
who was ur teacher????
im sure i'll have to give a composite nw....
anyway what was ur answer for tht C2Cl2F2 Q?? :?

 

[loly23]

@jerry
on the reactants side there is CxHy meaning yH so to get y on products side ther must be (y/2)H2o so that u get yH. got it?
I think i made a mistake in ststing the volumes i dont remember well..
so the volume of CO2 was 10,the volume of CxHy 10,the volume of C02 20
dividing by 10 and equating coefficient u get x=1 and (x+y/4)=2 giving y+4
hence CH4
hope u understand me,i cant make it any clearer

 

[loly23]

@SAn
im not sure of my ans but i broke the C-Cl bond since it is weaker than C-F to give Cl radical and and CClF2 radical


what u did?

 

[soumayya]

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

it's not y...it's y/2

 

[soumayya]

CxHy+(x+y/4)O2=xCO2+y/2H20
WELL GUYS I THKS ZAT ZE RITE EQN
I LOST MANY MARKS ON ZAT PAPER
ON QUEST NO4
IT ASKED 4 ZE SOLVENT I WAS PANICK
AND WRITE ZE PRODUCT
P5 WAS HORRIBLE WIZ ZE PLANNING
GUDLUCK 4 ZE REMAINING PAPER

for step 1..i put solvent water
for step 2...i put solvent CCl4
for step 3... i put solvent ethanol
don't knw if it's rite..

 

[skyfox]

i think the first solvent is water, and the other two are ethanol.

 

[blue]

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..

UMM ...if its said in the question tht its UNSATURATED then it is AN ALKENE!!! DOUBLE BONDS HELLO?
methane is saturated!!!!!!!!!!!!!!!!!

 

[mathmaster]

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

it's not y...it's y/2

yea sorry

 

[mathmaster]

CxHy+(x+y/4)O2=xCO2+y/2H20
WELL GUYS I THKS ZAT ZE RITE EQN
I LOST MANY MARKS ON ZAT PAPER
ON QUEST NO4
IT ASKED 4 ZE SOLVENT I WAS PANICK
AND WRITE ZE PRODUCT
P5 WAS HORRIBLE WIZ ZE PLANNING
GUDLUCK 4 ZE REMAINING PAPER

for step 1..i put solvent water
for step 2...i put solvent CCl4
for step 3... i put solvent ethanol
don't knw if it's rite..

solvents for halogenoalkane to
nitrile or CN- ethanol
alkene c=c NaOH
ammonia :NH3 ethanol

 

[colloquial]

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..

UMM ...if its said in the question tht its UNSATURATED then it is AN ALKENE!!! DOUBLE BONDS HELLO?
methane is saturated!!!!!!!!!!!!!!!!!

In the first question it didn't mention it was a hydrocarbon.. It has only mentioned that Michael Faraday has discovered a very flammable gas and decided to explode it to discover its identity.

You are mistaken with the question on standard enthalpy change of combustion, where it was mentioned that the hydrocarbon was unsaturated!! :|

 

[SAN]

@ loly23
omg ya i did the same thing...
so tell me who was ur chem teacher??? he seems to have dun a gud job

 

[JK_1995_15]

guys what a bout question 5

 

[JK_1995_15]

?