****Leaving Certificate Chemistry [All Levels] Before and After Discussion****

MacBizzle

booblefoop wrote: »

Is it that it had been made up to a solution of known concentration? That was a weird one, they usually ask what a primary standard is

Yeah that's it

Yulkmn

anyone know for the rates if u put the time on the bottom and temperature on the side if that's okey ??

mirrors

Yulkmn wrote: »

anyone know for the rates if u put the time on the bottom and temperature on the side if that's okey ??

No I'd say you'd lose a few marks

booblefoop wrote: »

Is it that it had been made up to a solution of known concentration? That was a weird one, they usually ask what a primary standard is

A solution with a known concentration

MacBizzle

Yulkmn wrote: »

anyone know for the rates if u put the time on the bottom and temperature on the side if that's okey ??

Wasn't it rate not time?

Yulkmn

MacBizzle wrote: »

Wasn't it rate not time?

it was 1/t
I put it on the x axis and put temperature on the y axis

MacBizzle

Yulkmn wrote: »

it was 1/t
I put it on the x axis and put temperature on the y axis

I think that's the right way, well that's what everyone in my class did. I did it the other way though and am nearly sure it's wrong :rolleyes:

TooMuchStudy

MacBizzle wrote: »

I think that's the right way, well that's what everyone in my class did. I did it the other way though and am nearly sure it's wrong :rolleyes:

is it not the value you set on the x-axis and the variable on the y-axis?

Peter Flynt

Everytime the world cup is on . . Soap appears - 2002, 2006, 2010, 2014. .

Yulkmn

TooMuchStudy wrote: »

is it not the value you set on the x-axis and the variable on the y-axis?

yeah the variable is the temp isn't it?
and did u get something like 66 seconds for the next part?

randylonghorn

Peter Flynt wrote: »

Everytime the world cup is on . . Soap appears - 2002, 2006, 2010, 2014. .

And in real life it's usually a conflict between the World Cup and the soaps in a lot of houses ... :pac:

MacBizzle

Yulkmn wrote: »

yeah the variable is the temp isn't it?
and did u get something like 66 seconds for the next part?

Did your graph start off steep and then get less steep or did it get steeper as it went on?

Apocladagr0

PhysicsKid99 wrote: »

What was the proper definition for standardised too, actually?

And what did people say for butane/propane differences? I said higher molecular mass and stronger Van der Waals forces for butane, was that right?

For standardised I said ' a soln. of precisely known concentration '.
I vaguely remember being told to be more detailed in a class test for that question but I couldn't remember what else to write:rolleyes:

I said more v.d.w. for butane too. I knew it was a six marker so they would probably be expecting two points but I couldn't think of another:o

Also for equilirium my x came out to be 0.9
So the #mol N2 at equil = 2-2x = 0.2 mol. ??

Inspector Coptoor

A very rough sketch of Q3
And the graph of rate vs temp.



For the butane vs propane question.
Id be saying higher Mr means more bonds meaning increased vdw forces which raises the bp

MacBizzle

Inspector Coptoor wrote: »

And the graph of rate vs temp.

That's the right way!?!

brian888

MacBizzle wrote: »

That's the right way!?!

could've fcuking sworn it was the opposite way round on the axes. Ah well, I only need a D3 anyways!

Yulkmn

MacBizzle wrote: »

That's the right way!?!

I put it as 1/t to be x-axis and it came out different like it went upwards from xaxis and kinda to the right in a curve

like I don't think you would lose a lot of marks if u did it the other way, cause it only said time vs temp

Peter Flynt

Since you're on the topic. . .

brian888

You sir, make me sad.

Yulkmn

Peter Flynt wrote: »

Since you're on the topic. . .

can you make one with the axis' switched around?

Inspector Coptoor

You could.
But it would be wrong

Yulkmn

Inspector Coptoor wrote: »

You could.
But it would be wrong

how tho? it just switching the axises

rainbowtrout

EoghanIRL wrote: »

Could you do the equilibrium calculation and see what answer you get . It would be great if you had time . I haven't seen the answer anywhere on here yet .

Chem equilibrium Q9

Inspector Coptoor

It would change the shape of the graph and tell an examiner the candidate didnt know a dependent variable from an independent variable

Peter Flynt

If you got the axes the wrong way around . . . Don't panic

In 2002 for the same experiment (although with rate against concentration rather than temperature) it stated this directly from the marking scheme.



See it there. . . "Rate can be on horizontal or vertical axis; similarly for concentration"

Inspector Coptoor

Talk about hand holding.
Who's doing the exam?
The candidates or the examiners?

That's like saying 2 + 2 = 4
Or 5

Yulkmn

Peter Flynt wrote: »

If you got the axes the wrong way around . . . Don't panic

In 2002 for the same experiment (although with rate against concentration rather than temperature) it stated this directly from the marking scheme.]

See it there. . . "Rate can be on horizontal or vertical axis; similarly for concentration"

thank you pheeeew do you know if there's attempt marks for the questions such as the equillbrium and the last part in Q1 the finding the value X ??

yoajing

Isn't brine needed to precipitate the soap?

Apocladagr0

rainbowtrout wrote: »

Chem equilibrium Q9

Don't you have to do 2-2x though, so final answer is 0.2 mol. ?

rainbowtrout

Apocladagr0 wrote: »

Don't you have to do 2-2x though, so final answer is 0.2 mol. ?

The question asks how many moles of nitrogen gas so 0.9 moles.

But it would be 0.2 moles if it asked for how many moles of NO at equilibrium

Yulkmn

Apocladagr0 wrote: »

Don't you have to do 2-2x though, so final answer is 0.2 mol. ?

you'll still get nearly full marks.
I did :
at equilibrium 2x = 1-x 1-x
then put it in and equaled it to 21 ( or what ever the kc was)
then I went on and did the -b formula
and got x to be 0.025 and 47 I disregarded the 47 and took the 0.025 and got 1-0.025 and which is .975.
anybody think I'll get any marks for that?