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

TheBegotten

True, but in general a balanced equation should be written as whole numbers. It's just that the heat of combustion definition required one mole of the substance being burnt.

rainbowtrout

Inspector Coptoor wrote: »

-2887.3 kJ/mol

54.6% water crystallization
The value of x was 6.97

4.59g Mac yield for soap.

I still can't believe how straight forward it was.

The Stoichiometry question in 10 b could have been on an OL paper.
12.6g - Mr was 252 so 0.05 moles and away you go from there.

Really hoping my students get a shed load of A1s

Totally agree. Nicest chemistry paper in years. Students in my school very happy.

TooMuchStudy

What type of catalysis is found in catalytic converters?

MacBizzle

TooMuchStudy wrote: »

What type of catalysis is found in catalytic converters?

Heterogenous.

Inspector Coptoor

TooMuchStudy wrote: »

What type of catalysis is found in catalytic converters?

Palladium
Platinum
Rhodium

Type of catalysis is heterogenous
Solid metal and gaseous exhaust fumes

Peter Flynt

TooMuchStudy wrote: »

What type of catalysis is found in catalytic converters?

Heterogeneous

It'd be nice if the useless muppets in the SEC would put this online.

MacBizzle

Peter Flynt wrote: »

Heterogeneous

It'd be nice if the useless muppets in the SEC would put this online.

D'you not take your paper with you?

Peter Flynt

MacBizzle wrote: »

D'you not take your paper with you?

I'm a teacher. I was supervising in a school which doesn't do chemistry

MacBizzle

Peter Flynt wrote: »

I'm a teacher. I was supervising in a school which doesn't do chemistry

Sorry, Sir.

TooMuchStudy

Right, I wrote heterocatalysis as I kept getting confused with heterogeneous and heterozygous, will I get it right?

EoghanIRL

TooMuchStudy wrote: »

Right, I wrote heterocatalysis as I kept getting confused with heterogeneous and heterozygous, will I get it right?

It's impossible to tell until the marking schemes come out .
Usually they put what they are looking for in bold on the marking scheme and they don't vary from it a lot .
I wouldn't think you'd get it to be honest but that's just my opinion.
They tend to be really strict with the marking scheme !

PhysicsKid99

Anyone else get 0.9 for moles in Q9?

Also; What was the use of brine in stage 3 of Q2?
And what was the precaution necessary for the end of the titration?
And I said free radical mechanism, is that right, for Q8?

I'm seriously scared here, I need a good grade in chemistry...

EoghanIRL

Peter Flynt wrote: »

I'm a teacher. I was supervising in a school which doesn't do chemistry

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 .

PhysicsKid99 wrote: »

Anyone else get 0.9 for moles in Q9?

Also; What was the use of brine in stage 3 of Q2?
And what was the precaution necessary for the end of the titration?
And I said free radical mechanism, is that right, for Q8?

I'm seriously scared here, I need a good grade in chemistry...

Brine is to dissolve sodium hydroxide .
Soap is precipitated in brine as it's insoluble in it .

For the precaution I said add drop wise when nearing end point so that one drop will cause a colour change . This way you will get an accurate measurement for volume of hcl . Do you think this is right .

I said substitution reaction but I see how it's probably wrong now

MacBizzle

EoghanIRL wrote: »

Brine is to dissolve sodium hydroxide .
Soap is precipitated in brine as it's insoluble in it .

For the precaution I said add drop wise when nearing end point so that one drop will cause a colour change . This way you will get an accurate measurement for volume of hcl . Do you think this is right .

I said substitution reaction but I see how it's probably wrong now

I think it is substitution reaction...

DamoSquad

EoghanIRL wrote: »

Brine is to dissolve sodium hydroxide .
Soap is precipitated in brine as it's insoluble in it .

For the precaution I said add drop wise when nearing end point so that one drop will cause a colour change . This way you will get an accurate measurement for volume of hcl . Do you think this is right .

I said substitution reaction but I see how it's probably wrong now

I said free radical substitution.... best of both worlds!

PhysicsKid99

EoghanIRL wrote: »

Brine is to dissolve sodium hydroxide .
Soap is precipitated in brine as it's insoluble in it .

For the precaution I said add drop wise when nearing end point so that one drop will cause a colour change . This way you will get an accurate measurement for volume of hcl . Do you think this is right .

I said substitution reaction but I see how it's probably wrong now

Okay, thank you I initially had substitution reaction, but then I saw mechanism so I wasn't sure... I said the same thing for the titration though

epen2k9

EoghanIRL wrote: »

It's impossible to tell until the marking schemes come out .
Usually they put what they are looking for in bold on the marking scheme and they don't vary from it a lot .
I wouldn't think you'd get it to be honest but that's just my opinion.
They tend to be really strict with the marking scheme !

Nope I don't think you will get it right because last year I did my chemistry and I put 'hetero' instead of 'hetreogenous catalysis' I got it wrong.. I looked up the marking scheme and it says 'Hetero = 0 marks"

Peter Flynt

rainbowtrout wrote: »

Nicest chemistry paper in years.

I wouldn't agree with that

CiaraMT

Does anyone know if chemistry works like maths? Will you get most of the marks for the method even if your finally answer's wrong? Thanks

kev44

In equilibrium my answer for X was 1.64

CL987

Is saponification and base hydrolysis the same thing? I wrote down both in the exaam

PhysicsKid99

CL987 wrote: »

Is saponification and base hydrolysis the same thing? I wrote down both in the exaam

I always learned 'base catalysed hydrolysis' but I'm sure they're the same

scallway

kev44 wrote: »

In equilibrium my answer for X was 1.64

I got the same!

TheRedDevil10

MacBizzle wrote: »

Heterogenous.

Is surface adsorption also right ?

MacBizzle

TheRedDevil10 wrote: »

Is surface adsorption also right ?

Wasn't that for the next part of the question? I wrote that down somewhere anyway but it was a complete guess.

Daniel2590

CL987 wrote: »

Is saponification and base hydrolysis the same thing? I wrote down both in the exaam

Yep saponification = alkaline/base hydrolysis

rainbowtrout

Peter Flynt wrote: »

Heterogeneous

It'd be nice if the useless muppets in the SEC would put this online.

Papers are put up at 7 each evening

Yulkmn

hey all,
is there attempt marks for the percentage of crystals and the value of X ?
also what if you put 1/t on the x axis and the temperature on the Y axis for the rates question?

PhysicsKid99

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?

booblefoop

PhysicsKid99 wrote: »

What was the proper definition for standardised too, actually?

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