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

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Comments

  • #272
    TheBegotten
    Registered Users, Registered Users 2 Posts: 541 ✭✭✭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.


  • #273
    rainbowtrout
    Registered Users, Registered Users 2 Posts: 15,465 ✭✭✭✭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.


  • #274
    TooMuchStudy
    Registered Users, Registered Users 2 Posts: 82 ✭✭TooMuchStudy


    What type of catalysis is found in catalytic converters?


  • #275
    MacBizzle
    Closed Accounts Posts: 913 ✭✭✭MacBizzle


    TooMuchStudy wrote: »
    What type of catalysis is found in catalytic converters?

    Heterogenous.


  • #276
    Inspector Coptoor
    Registered Users, Registered Users 2 Posts: 6,818 ✭✭✭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


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  • #277
    Peter Flynt
    Registered Users, Registered Users 2 Posts: 3,232 ✭✭✭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.


  • #278
    MacBizzle
    Closed Accounts Posts: 913 ✭✭✭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?


  • #279
    Peter Flynt
    Registered Users, Registered Users 2 Posts: 3,232 ✭✭✭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


  • #280
    MacBizzle
    Closed Accounts Posts: 913 ✭✭✭MacBizzle


    Peter Flynt wrote: »
    I'm a teacher. I was supervising in a school which doesn't do chemistry

    Sorry, Sir. :o


  • #281
    TooMuchStudy
    Registered Users, Registered Users 2 Posts: 82 ✭✭TooMuchStudy


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


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  • #282
    EoghanIRL
    Registered Users, Registered Users 2 Posts: 4,080 ✭✭✭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 !


  • #283
    PhysicsKid99
    Registered Users, Registered Users 2 Posts: 20 ✭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...


  • #284
    EoghanIRL
    Registered Users, Registered Users 2 Posts: 4,080 ✭✭✭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 :(


  • #285
    MacBizzle
    Closed Accounts Posts: 913 ✭✭✭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...


  • #286
    DamoSquad
    Registered Users, Registered Users 2 Posts: 2 ✭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!


  • #287
    PhysicsKid99
    Registered Users, Registered Users 2 Posts: 20 ✭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 :D


  • #288
    epen2k9
    Registered Users, Registered Users 2 Posts: 11 ✭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"


  • #289
    Peter Flynt
    Registered Users, Registered Users 2 Posts: 3,232 ✭✭✭Peter Flynt


    rainbowtrout wrote: »
    Nicest chemistry paper in years.

    I wouldn't agree with that


  • #290
    CiaraMT
    Registered Users, Registered Users 2 Posts: 13 ✭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 :)


  • #291
    kev44
    Registered Users, Registered Users 2 Posts: 61 ✭✭kev44


    In equilibrium my answer for X was 1.64


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  • #292
    CL987
    Registered Users, Registered Users 2 Posts: 6 ✭CL987


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


  • #293
    PhysicsKid99
    Registered Users, Registered Users 2 Posts: 20 ✭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


  • #294
    scallway
    Registered Users, Registered Users 2 Posts: 20 ✭scallway


    kev44 wrote: »
    In equilibrium my answer for X was 1.64

    I got the same!


  • #295
    TheRedDevil10
    Registered Users, Registered Users 2 Posts: 1,261 ✭✭✭TheRedDevil10


    MacBizzle wrote: »
    Heterogenous.

    Is surface adsorption also right ?


  • #296
    MacBizzle
    Closed Accounts Posts: 913 ✭✭✭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.


  • #297
    Daniel2590
    Registered Users, Registered Users 2 Posts: 1,645 ✭✭✭Daniel2590


    CL987 wrote: »
    Is saponification and base hydrolysis the same thing? I wrote down both in the exaam

    Yep saponification = alkaline/base hydrolysis


  • #298
    rainbowtrout
    Registered Users, Registered Users 2 Posts: 15,465 ✭✭✭✭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


  • #299
    Yulkmn
    Registered Users, Registered Users 2 Posts: 101 ✭✭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?


  • #300
    PhysicsKid99
    Registered Users, Registered Users 2 Posts: 20 ✭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?


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  • #301
    booblefoop
    Registered Users, Registered Users 2 Posts: 52 ✭✭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 :/


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