How's Chemistry Paper 52?

[A2candidate]

duhh..my teacher made me feel xtremely nervous..she told me that i must vary the solid mass not the water like i wrote at first...

Yeah.. Tht's true, i think that the purpose they give a fixed mass of water is for us to vary the amount of KCL added lol.. Besides, the volume of each experiment is supposed to be constant as a control and thats why the limiting factor is that the total volume couldn't have been exactly the same as those having high concentrations of KCL will have a slightly greater volume. Thats what i think though rofl.. Is this a silly logic??

 

[|Riddler|]

maths p3 is usuall 60 out of 75 for A bt im nt sure

 

[Bilawal]

itz really confusing!!!! even if u gtg abv 80s in paper its possible nt to score an A still!!!!

smtimz itz on 55____ well i lost 10 marks strait away____p-4 was awsm!!! wat u say any chances on A star___ in AS gt an A in maths

 

[|Riddler|]

i wrote the limitng factor that v canot use a mas of kcl so high that it doznt dissolve in watr but i thnk that is wrong

 

[XWTBSILT]

Paper was good

Hey wat was the hazard i just did a guess on KCl :!: :roll:
IS KCl in the first place dangerous :?:

Wat was the comment ull write in the very last question. :?:

 

[kikie209]

duhh..my teacher made me feel xtremely nervous..she told me that i must vary the solid mass not the water like i wrote at first...

Yeah.. Tht's true, i think that the purpose they give a fixed mass of water is for us to vary the amount of KCL added lol.. Besides, the volume of each experiment is supposed to be constant as a control and thats why the limiting factor is that the total volume couldn't have been exactly the same as those having high concentrations of KCL will have a slightly greater volume. Thats what i think though rofl.. Is this a silly logic??

yup..that's exactly what my teacher said..the reason they gave fixed mass of water is for us to make it constant..and that will become the limiting factor later question..and no fixed mass of solid KCL bcoz they want us to vary the mass..well i think either way should be correct as well..at least the resulted concentration is varied, right?

 

[Jazib]

ofcourse, an increasing trend, n Y intercept at 100 will earn both marks!
so, shape of the line is not any problem to discuss...

 

[Jazib]

i wrote the limiting factor is dat, mass of KCl shud not b greater than 100 g.
n the hazard i wrote, due to over heating solution may spill (though i think its wrong, but cudnt think of nything else dat time).

 

[Smart_Sam]

I'm just asking,
Can the limiting factor be that as "limited water is being used, so a limited amount of mass of KCL can be dissolve, thus limiting the Concentration/Molality of the solution, as solution may get saturated at point"?
Is this correct because As (i think) this acknowledges the fact that water was limited and also explains the consequence that limited water would cause.

 

[Jazib]

well... "qualitatively" speaking, ur answer is ok! now i dun have any idea if examiner is xpecting a qualitative, or a quantitative answer.

 

[thebadguy]

the hazard i wrote was "since we are heating a container which is closed with a lid to avoid any heat losses, therefore if the pressure inside the container increases too much, it will blow up..."
is this correct? :S

 

[Jazib]

huh :S u didnt get the xperiment man! y on earth u put a lid on a boiling water (which had relation with atmospheric pressure).

 

[stud91]

I wrote that KCl is poisonous so handle it with care. I read some where that KCl is used in lethal injections. Is it correct??

 

[apple]

huh :S u didnt get the xperiment man! y on earth u put a lid on a boiling water (which had relation with atmospheric pressure).

Not atmospheric pressure...external pressure...the pressure of the surroundings.

Besides, for an equilibrium to be achieved, a closed system is required.

 

[Jazib]

err. if ur boiling it, then it should b closed? i dunno!

 

[stud91]

@apple Pressure would increase gradually if u put a lid unless you incorporate a manometer with it [which by the way is not available in school labs]. And by the way pressure of surroundings is atmospheric pressure which is constant..

 

[Jazib]

yeah, dats y i thnk i did it right!

 

[sharjeel akhtar]

it was one of d easiest paper in history.
Em not losing more dan 5 marks,INSHALLAH