chemistry p22

[alisattar7]

How did it go ?

 

[roshani]

the quetion was tooo tough like hel..

 

[matchwhiz]

hey to calculate enthalpy change(E=mcT) what volume did u use as mass 20 or 30 cm3
and what is the second structural formula 4 the first question(C2H4O2 molecular formula)

 

[lychee26]

i messed up question one. And i took 30

 

[reh2300]

what was the answer for the enthaply change?? what mass were we suppose to take??

 

[lychee26]

it was positive 189 something. What about you? And we were supposed to use thr volume that was 30

 

[alisattar7]

first structural formula had a carboxylic acid the other one had an ester..
umm i used 30cm but not really sure if i did it correctly..it was like 30*4.18*5.2(temp.change)

empirical form was ch2o

i messed up the last question. :/

 

[alisattar7]

The paper was really wierd full of calculations,and i **** at them

 

[lychee26]

first structural formula had a carboxylic acid the other one had an ester..
umm i used 30cm but not really sure if i did it correctly..it was like 30*4.18*5.2(temp.change)

empirical form was ch2o

i messed up the last question. :/

yeah thats exactly how i did question 3. My empirical formula was wrong. That me
ans i must have done something wrong in the previoud parts. Oh btw which element did you write ?

 

[alisattar7]

geramnium.u?

 

[lychee26]

Se which is obviously wrong. Wha
t was the sign of your enthalpy change?

 

[ching293]

i didnt take as this year, my country doing paper23, they said it was so easy :S

 

[Nuh3194]

I messed up the first question. I dont know if what i did was right.
For the very last organic question, howcome they were 3 steps? First step was sustitution of NH3 with OH group, and second step was oxidation of the aldehyde to Carboxylic acid. Can anyone tell me what I missed?

 

[reh2300]

but the volume was in excess! so should we use it?

 

[ourvesh7]

U should use volume 30cm3! refer 2 definition!
final answer is +79.0!
the other structure is methylmethanal! ester

 

[reh2300]

wat was the total mark for that enthalpy question?

 

[matchwhiz]

u should expect this kind of paper since paper 4 lack calculation
n 189 is not the answer i hv got 62 i think

 

[anahita16]

I got empirical formula CH20, molecular formula formula C3H6O3 and Mr was 59.9. Anyone got the same?? :unknown:

 

[reh2300]

yup i got the same

 

[reh2300]

now can sum1 plz tell me wat the total mark was for the enthalpy question coz i messed it up! :S