GT for Chemistry paper 22 AS.

[Mustehssun Iqbal]

It was -129 100%

hmm...

 

[Mustehssun Iqbal]

there is an enthalpy change when H2 goes to H2O and thats what we apply in hesses aw when using values of combustion...it was -129

but there was no H2O in the equation! I looked that up like 3 or 4 times searching for H2O. :/

 

[00tanveer]

Normal conditions are room temperature (around 25degrees) and 1 atomsphere or pressure. The conditions quoted were both higher, way high. So yeah, the rate of formation of methanol would increase in all cases. And for the UPTEENTH TIME, the second reaction was NOT a reversible reaction!!!!! (this is for those who adamantly keep sayin it's an equilibrium).

 

[00tanveer]

Yeah

 

[Pals_1010]

It was -129 100%

Yup I did it like hundred times : -129 confirmed

 

[littlecloud11]

One more thing about enthalpy change. How was it 129, + or -. mine was coming 400 something
I asked some candidate( s ) who got 129 kJper mol , but they took also the enthalpy change of combustion of H2( g ) while making the cycle ( Hess's law ). I thought data of enthalpy change of combustion of H2( g ) was a trick! Because there's no enthalpy change from H2 ( g ) to H2 ( g )!
Anyone else got this??

ofcourse there is an enthalpy change of combustion for H2. It forms water on combustion. and since there was 2 moles of H2 you had to multiply the value by two. the answer was -129

 

[robotic94]

I hadn't notice it was SKELETAL formula that was asked for the cis-trans isomer(silly mistake I know) but I saw it like when 5 mins was left, and I hastily drew these. Do you think I'll get my marks?

so what you made is wrong?
because i made the same as youurs!

 

[00tanveer]

Solvents is correct.

 

[Mustehssun Iqbal]

ofcourse there is an enthalpy change of combustion for H2. It forms water on combustion. and since there was 2 moles of H2 you had to multiply the value by two. the answer was -129

2 moles of H2?? H2O ?? I looked up for both of these points, as far as I remember.
maybe I should wear glasses from now on

 

[Pals_1010]

so what you made is wrong?
because i made the same as youurs!

Am not too sure... Because I made these in a hurry (last 5 mins).... Someone on this forum told me you are not supposed to put C and H atoms in a skeletal formula... You drew exactly the same thing?

 

[00tanveer]

The carbon-carbon double bond needs to be shown in a structural formula coz it's a functional group.

 

[JD REBORN]

I wanted to ask that when drawing optical isomers can someone tell me that marks will be deducted for drawing a methyl group as CH3 rather than showing all the 3 bond between carbon and hydrogen

 

[littlecloud11]

2 moles of H2?? H2O ?? I looked up for both of these points, as far as I remember.
maybe I should wear glasses from now on

There was no H2O in the equation. but the chart gave the enthalpy of combustion values, so you ha d to include both CO2 and H2O in the Hess's cycle.

 

[Mustehssun Iqbal]

There was no H2O in the equation. but the chart gave the enthalpy of combustion values, so you ha d to include both CO2 and H2O in the Hess's cycle.

right

 

[saurabh]

Guys for the reaction part in Q 3 i wrote Elimination, oxidation and addition.....Are they correct?

i wrote the same i think addtion and oxidation are correct elimination m also doubtful!

 

[00tanveer]

Nope!!! I think it was 1 or was it??? Can't remember, littlecloud!

 

[robotic94]

Am not too sure... Because I made these in a hurry (last 5 mins).... Someone on this forum told me you are not supposed to put C and H atoms in a skeletal formula... You drew exactly the same thing?

Yes yes exactly the same thing :|

 

[Pals_1010]

i wrote the same i think addtion and oxidation are correct elimination m also doubtful!

In this case, either elimination or dehydration is acceptable.... Mark schemes often allow one or two options

 

[Pals_1010]

Yes yes exactly the same thing :|

Let's not worry too much about that okay? There's still P4 ahead

 

[robotic94]

Bahahaha xD no one might have done this silly mistake i left the emperical formula as CHO because i thought its 1, 1.33, 1.14
Oh shit -_- PFFTTHH
the GT has to be loww inshaAllah