The Haber Process Question (2 Viewers)

[fadykozman]

no problemo, pleasure to help

 

[kouklitsa]

ur all wrong.... wen volume decreases conc of ALL reactants increase as
conc proportional to moles/volume

the 3 conc then curve
NH3 curve concave down
H2 and H2 concave up

OMG A SMART PERSON... totally agree by decreasing volume the IMMEDIATE effect is that the concentration would be increas because c=n/v so if u decrease V then C goes up .. then Le chat's principle works!!!

 

[seadonkey]

Dear SeaDonkey




The equilib constant doesn't change with change in volume or concentration, it only varies with the temperature, thus the basis of your argument are gone!

I can understand your point that concentration of all products and reactants increase.

umm i sed K doesnt change?

 

[fadykozman]

what you said is "How can you keep K constant when equilibrium shift?" even if the equilibrium shifts, the K doesn't change... read your post again

 

[seadonkey]

what you said is "How can you keep K constant when equilibrium shift?" even if the equilibrium shifts, the K doesn't change... read your post again

read the whole sentence at once... then ull understand wat i mean

 

[alia]

haber process

i spoke to my chemistry teacher and she said that the concentration of everything had to go up a little bit in a straight line to indicate that the volume of the vessel had changed. (less volume --> higher concentration) Then you have to show what happens with increased pressre. (increased production of ammonia, and decrease in N2 and H2 to make ammonia)

 

[Captain Karl]

And thats the end of that chapter....

Did she say anything about molar ratios?

 

[alia]

haber process

no I forgot to ask about thatbut i hope we dont have to show that the reaction reaches equilibrium again, but knowing how the HSC markers mark chem i bet it will be needed. They are so picky

 

[justchillin]

Yeah looks ok to me...but remember u had 2 define Le Chatiler's principal before applying it in ur explanation...

 

[Captain Karl]

I wrote that the equilibrium is re-established (after explaining Le Chatiler's principle) but I forgot to draw in the graph that its re-established. I think it depends on the marker and the marking quidelines as to whether they'll that kinda stuff slide

 

[queenie]

OH, holy crap he's right, all concentrations should have shot up by a little at first, then gone up/down according to LCP, then eqm established.

SHIT!

but, as captain karl said, it was worth 2 marks.. i guess it all depends on the marking guidelines

 

[alia]

haber proccess

It was 2 marks for the graph and 2 marks for the explanation, so maybe if u show that it goes up and ammonia increases and the N2 and H2 decrease then maybe u might get 2 marks, but then again maybe u would need to est equilibrium as well ... and explain it

 

[~ ReNcH ~]

It's probably taken for granted that the system reaches equilibrium again, so I don't think that'll be part of the criteria for the graph (possibly for the explanation though). It'll probably be 1 mark for the right concavity/direction, and 1 mark for showing an initial increase in the concentration of all reactants and products. I doubt whether indicating the correct molar ratio will be part of the criteria because:
a) it was a sketch
b) it wasn't indicated on the diagram on the exam paper in the first place

 

[queenie]

did many of you guys put the initial increase/decrease in products and reactants?

 

[kouklitsa]

did many of you guys put the initial increase/decrease in products and reactants?

i did, and it only sounds like a few other people.. sounds like the majority of the people ive talked to from my school and everything just did a straight out Le Chat. type of thing rather than an initial increase in volume of all reactants.

 

[~ ReNcH ~]

did many of you guys put the initial increase/decrease in products and reactants?

I did mine like Captain Gh3y - no initial increase. We'll probably only lose 1 mark at most, but who knows...the markers might be lenient

 

[fadykozman]

very much doubted...

 

[queenie]

very much doubted...

wat that the markers will be lenient?

 

[Abtari]

i doubt they will be pedantic..

*sigh* the hsc exams this year were riddled with little tricks - chem, physics, bio... definitely tougher than last year, in my opinion.

 

[~ ReNcH ~]

i doubt they will be pedantic..

*sigh* the hsc exams this year were riddled with little tricks - chem, physics, bio... definitely tougher than last year, in my opinion.

I didn't do Physics and Bio, but I do agree that our Chem exam was harder than last year's. Generally science teachers are pedantic and that's what makes it so difficult to get high marks in Chem/Phys/Bio .