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**Chemistry...Before/After

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    #62
    FaoiSin
    Registered Users Posts: 789 ✭✭✭FaoiSin


    finality wrote: »
    I really think we did them. Or else I'm just visualizing them too well :L

    The chemicals weren't banned until the end of 5th year so maybe you did them before then?


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    #63
    reznov
    Registered Users Posts: 921 ✭✭✭reznov


    finality wrote: »
    I really think we did them. Or else I'm just visualizing them too well :L

    We did them! You're not delusional just yet.


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    #64
    dmca93
    Closed Accounts Posts: 104 ✭✭dmca93


    We also did them, before and after we were told the chemicals were banned, cause we'd be hard like that! :cool:


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    #65
    Random_Person
    Registered Users Posts: 328 ✭✭Random_Person


    Hayezer wrote: »
    Apparently ethanal and winkler(dissolved O2) sre coming up, not sure about the other :P

    The ones I think may come up, going by past years/patterns etc. are:

    -Relative Mr. of a volatile liquid
    -Water of Crystallisation
    -Heat of Reaction
    -Ethanal
    -Ethanoic Acid
    -Dissolved Oxygen
    -Free Chlorine/Suspended + Dissolved solids
    -Rate of Reaction with Hydrogen Peroxide

    I'll be making sure I have these perfect anyway..


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    #66
    FaoiSin
    Registered Users Posts: 789 ✭✭✭FaoiSin


    I'm sure that Orange to Green colour change was well worth working with carcinogens ;)


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    #67
    Random_Person
    Registered Users Posts: 328 ✭✭Random_Person


    YeaaahFaoiSin wrote: »
    I'm sure that Orange to Green colour change was well worth working with carcinogens ;)

    How Ironic would it be if that experiment came up on the paper and then the next day you got diagnosed with cancer..

    Actually, that would be pretty bad.. but ironic nonetheless.. :pac:


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    #68
    ashalingable
    Registered Users Posts: 21 ✭ashalingable


    I'm starting to get really worried about the chemistry paper :(

    any tips/advice...ANYTHING would be appreciated!


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    #69
    ChemHickey
    Closed Accounts Posts: 3,479 ✭✭✭ChemHickey


    ashalingable wrote: »
    I'm starting to get really worried about the chemistry paper :(

    any tips/advice...ANYTHING would be appreciated!

    Be calm. relax. Learn your organic as it can help in many other sections. I'd recommend doing lots of exam paper questions as they're very very very repetitive. Also, look over water and rates of reactions too.


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    #70
    ChemHickey
    Closed Accounts Posts: 3,479 ✭✭✭ChemHickey


    Random_Person wrote: »
    How Ironic would it be if that experiment came up on the paper and then the next day you got diagnosed with cancer..

    Actually, that would be pretty bad.. but ironic nonetheless.. :pac:

    We've all worked with phenolphthalein... NO-ONE IS SAFE:eek:


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    #71
    FaoiSin
    Registered Users Posts: 789 ✭✭✭FaoiSin


    ChemHickey wrote: »
    We've all worked with phenolphthalein... NO-ONE IS SAFE:eek:

    Would I be right in saying that anything that has benzene in it is dangerous :P


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    #72
    ChemHickey
    Closed Accounts Posts: 3,479 ✭✭✭ChemHickey


    YeaaahFaoiSin wrote: »
    Would I be right in saying that anything that has benzene in it is dangerous :P

    Pretty much, the Phenyl- functional group!


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    #73
    ei.sderob
    Closed Accounts Posts: 108 ✭✭ei.sderob


    I myself, enjoy the humorous side to chemistry. For example, the classic "My name is Bond - Covalent Bond." gets me every time. I'm thinking of writing plenty of witty anecdotes in the margins of my answer booklet to warm up to the lad/lass marking my test :P


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    #74
    Monsieur Folie
    Registered Users Posts: 1,988 ✭✭✭Monsieur Folie


    ei.sderob wrote: »
    I myself, enjoy the humorous side to chemistry. For example, the classic "My name is Bond - Covalent Bond." gets me every time. I'm thinking of writing plenty of witty anecdotes in the margins of my answer booklet to warm up to the lad/lass marking my test :P

    I'd always be worried I'd get a dry shíte examiner who doesn't take kindly to it and then searches for marks to deduct!

    What do you do with a dead chemist? You barium.. =P

    Heisenberg was driving down a motorway when he was pulled over by the police for speeding. The policeman comes to the window and asks ''do you know how fast you were going there?" Heisenberg replies "no, but I know exactly where I am!"

    I love cheesy chemistry jokes. :D


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    #75
    finality
    Registered Users Posts: 1,763 ✭✭✭finality


    You know the way half the questions on the chemistry paper aren't numbered? How are you supposed to structure your paper? Like do you write part of the question and then the answer or something? It's really annoying that they can't just number the damn questions.


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    #76
    moll_bangers
    Registered Users Posts: 31 ✭moll_bangers


    ei.sderob wrote: »
    I myself, enjoy the humorous side to chemistry. For example, the classic "My name is Bond - Covalent Bond." gets me every time. I'm thinking of writing plenty of witty anecdotes in the margins of my answer booklet to warm up to the lad/lass marking my test :P
    What do you call a tooth in a glass of water? A one molar solution :D awh I love nerdy chemistry jokes!


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    #77
    ei.sderob
    Closed Accounts Posts: 108 ✭✭ei.sderob


    Hahaha, they're the best kind of jokes!! Gold walks into a bar, the barman says "A..u, get out!" On a serious note though, the final experiment in the Water chapter, colorimeter or the other one? Tis the last thing I've got to do before the exam.


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    #78
    Monsieur Folie
    Registered Users Posts: 1,988 ✭✭✭Monsieur Folie


    finality wrote: »
    You know the way half the questions on the chemistry paper aren't numbered? How are you supposed to structure your paper? Like do you write part of the question and then the answer or something? It's really annoying that they can't just number the damn questions.

    It's the same in Physics and I hate it when they do that! I always just answer with bullet points for each part, and if it's not clear, I'll put in the essence of the question in just to be sure (but usually that's not necessary).


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    #79
    moll_bangers
    Registered Users Posts: 31 ✭moll_bangers


    finality wrote: »
    You know the way half the questions on the chemistry paper aren't numbered? How are you supposed to structure your paper? Like do you write part of the question and then the answer or something? It's really annoying that they can't just number the damn questions.

    I make my own numberings like calling it 2b(i) or something because I know if I don't something will be left out :/


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    #80
    ChemHickey
    Closed Accounts Posts: 3,479 ✭✭✭ChemHickey


    finality wrote: »
    You know the way half the questions on the chemistry paper aren't numbered? How are you supposed to structure your paper? Like do you write part of the question and then the answer or something? It's really annoying that they can't just number the damn questions.

    Just go

    (i) ~~~~~~~~
    ^^^^^^^^
    **********
    (ii) +++++++++++++++++++++++++++++++++++++++++++++++++++++++



    Where each symbol represents a different part of the question.. if yano what I mean,, :K


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    #81
    partyatmygaff
    Registered Users Posts: 10,992 ✭✭✭✭partyatmygaff


    YeaaahFaoiSin wrote: »
    Would I be right in saying that anything that has benzene in it is dangerous :P
    ChemHickey wrote: »
    Pretty much, the Phenyl- functional group!
    In case a question like that actually comes up... Aromatic rings are found in a huge number of natural compounds in the body (aromatic amino acids for example) and in an even larger number of relatively safe compounds like benzoic acid, aspirin and paracetamol.

    It'd be very wrong to assume that everything with a phenyl group is toxic.


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    #82
    FaoiSin
    Registered Users Posts: 789 ✭✭✭FaoiSin


    partyatmygaff wrote: »
    In case a question like that actually comes up... Aromatic rings are found in a huge number of natural compounds in the body (aromatic amino acids for example) and in an even larger number of relatively safe compounds like benzoic acid, aspirin and paracetamol.

    It'd be very wrong to assume that everything with a phenyl group is toxic.

    Fair enough! :D


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    #83
    leaveiton
    Closed Accounts Posts: 1,778 ✭✭✭leaveiton


    finality wrote: »
    You know the way half the questions on the chemistry paper aren't numbered? How are you supposed to structure your paper? Like do you write part of the question and then the answer or something? It's really annoying that they can't just number the damn questions.

    I usually just leave a line between the two different parts, or I do it in bullet points, depending on how I'm feeling :pac:


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    #84
    ChemHickey
    Closed Accounts Posts: 3,479 ✭✭✭ChemHickey


    partyatmygaff wrote: »
    In case a question like that actually comes up... Aromatic rings are found in a huge number of natural compounds in the body (aromatic amino acids for example) and in an even larger number of relatively safe compounds like benzoic acid, aspirin and paracetamol.

    It'd be very wrong to assume that everything with a phenyl group is toxic.

    Ya I suppose I was jumping in there a bit too soon, anyway, Phenyl- isn't on our course so we don;t need to worry! :L


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    #85
    ei.sderob
    Closed Accounts Posts: 108 ✭✭ei.sderob


    Is Toluene not a carcinogen or is it just less carcinogenic than benzene itself? Hoping the paper is kind, need the A1.


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    #86
    partyatmygaff
    Registered Users Posts: 10,992 ✭✭✭✭partyatmygaff


    ei.sderob wrote: »
    Is Toluene not a carcinogen or is it just less carcinogenic than benzene itself? Hoping the paper is kind, need the A1.
    Almost any compound can be carcinogenic. Even relatively safe drugs like paracetamol are carcinogenic (But only very mildly to the point of insignificance).

    Now as for toluene and benzene... Toluene is relatively non-carcinogenic. Benzene on the other hand is carcinogenic.

    There's a very good reason to explain that but for that reason to make any sense you need to appreciate a few details first.
    • In the metabolism of foreign chemicals (Known as xenobiotics) such as drugs or benzene/toluene, oxidation is a very common reaction. A huge number of chemicals are oxidised by the Cytochrome P450 supergroup of enzymes.
    • In many cases, the metabolite and not the original molecule causes the toxicity. This is the case with benzene.
    • As a general rule, the body wants to make xenobiotics less reactive and more water soluble. Oxidation and the presence of oxygen in the resulting molecule makes the compound more polar and introduces hydrogen bonding sites. This has the effect of making the compound far more water soluble (Which will allow it to much more readily dissolve in the urine) but also has the effect of making the molecule quite a bit more reactive.
    • Cell growth, division and differentiation is strictly controlled by proteins and other biochemicals. An "error" in any of the proteins involved will lead to either cell death (Which *shouldn't* cause major issues) or a loss of control leading to further errors and damage leading to tumour formation and cancer. Interactions with the other involved biochemicals may also lead to abnormal behavior.
    • "Errors" in the proteins involved most commonly arise from aberrations in the DNA sequence that codes for them in the genome. These may be spontaneous aberrations or aberrations induced by a chemical or physical agent (Such as ionising radiation).
    Now, remember that cancer is the uncontrolled replication of cells. Then, consider the structures of benzene and toluene. Benzene is an unsubstituted aromatic ring whereas toluene has a methyl side chain.

    Bearing in mind what I said earlier about oxidation being an important reaction in metabolism. If I oxidise toluene, I get benzyl alcohol followed by benzaldehyde and then benzoic acid (Sound familiar?). As you're already aware, benzoic acid isn't toxic. That said, it's not readily excreted from the body as it has very poor solubility in water. Benzoic acid is converted to the more polar (Hence more water soluble) hippuric acid before being excreted in the urine. All in all, it's fairly non-toxic and not too dangerous to life.

    Benzene on the other hand has a completely different and far more complicated metabolic pathway with a lot of toxic intermediates. If I oxidise benzene, I first get two compounds called benzene oxide / oxepin. These set of molecules can then go down a number of different routes. If the molecule is further oxidised it is converted to hydroquinone (Which used to be used as a skin lightening agent). Hydroquinone is then further oxidised to para-benzoquinone. Para-benzoquinone is one of the main toxic metabolites of benzene. Not to get any more specific but para-benzoquinone (Better known as p-quinone) and its derivatives disrupt cell growth and division. Interestingly, this toxicity to cells led to the development of a new class of anti cancer drugs based on p-quinone.

    I went on in a bit too much detail there but hopefully you'll all find it an interesting read. None of that is actually needed for LC Chemistry but understanding why one is toxic and one isn't is better than "just knowing"!


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    #87
    UnholyGregor
    Registered Users Posts: 492 ✭✭UnholyGregor


    a1


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    #88
    Coeurdepirate
    Registered Users Posts: 2,576 ✭✭✭Coeurdepirate


    Hoping for a D tbh! :p


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    #89
    ei.sderob
    Closed Accounts Posts: 108 ✭✭ei.sderob


    partyatmygaff wrote: »
    Almost any compound can be carcinogenic. Even relatively safe drugs like paracetamol are carcinogenic (But only very mildly to the point of insignificance).

    Now as for toluene and benzene... Toluene is relatively non-carcinogenic. Benzene on the other hand is carcinogenic.

    There's a very good reason to explain that but for that reason to make any sense you need to appreciate a few details first.
    • In the metabolism of foreign chemicals (Known as xenobiotics) such as drugs or benzene/toluene, oxidation is a very common reaction. A huge number of chemicals are oxidised by the Cytochrome P450 supergroup of enzymes.
    • In many cases, the metabolite and not the original molecule causes the toxicity. This is the case with benzene.
    • As a general rule, the body wants to make xenobiotics less reactive and more water soluble. Oxidation and the presence of oxygen in the resulting molecule makes the compound more polar and introduces hydrogen bonding sites. This has the effect of making the compound far more water soluble (Which will allow it to much more readily dissolve in the urine) but also has the effect of making the molecule quite a bit more reactive.
    • Cell growth, division and differentiation is strictly controlled by proteins and other biochemicals. An "error" in any of the proteins involved will lead to either cell death (Which *shouldn't* cause major issues) or a loss of control leading to further errors and damage leading to tumour formation and cancer. Interactions with the other involved biochemicals may also lead to abnormal behavior.
    • "Errors" in the proteins involved most commonly arise from aberrations in the DNA sequence that codes for them in the genome. These may be spontaneous aberrations or aberrations induced by a chemical or physical agent (Such as ionising radiation).
    Now, remember that cancer is the uncontrolled replication of cells. Then, consider the structures of benzene and toluene. Benzene is an unsubstituted aromatic ring whereas toluene has a methyl side chain.

    Bearing in mind what I said earlier about oxidation being an important reaction in metabolism. If I oxidise toluene, I get benzyl alcohol followed by benzaldehyde and then benzoic acid (Sound familiar?). As you're already aware, benzoic acid isn't toxic. That said, it's not readily excreted from the body as it has very poor solubility in water. Benzoic acid is converted to the more polar (Hence more water soluble) hippuric acid before being excreted in the urine. All in all, it's fairly non-toxic and not too dangerous to life.

    Benzene on the other hand has a completely different and far more complicated metabolic pathway with a lot of toxic intermediates. If I oxidise benzene, I first get two compounds called benzene oxide / oxepin. These set of molecules can then go down a number of different routes. If the molecule is further oxidised it is converted to hydroquinone (Which used to be used as a skin lightening agent). Hydroquinone is then further oxidised to para-benzoquinone. Para-benzoquinone is one of the main toxic metabolites of benzene. Not to get any more specific but para-benzoquinone (Better known as p-quinone) and its derivatives disrupt cell growth and division. Interestingly, this toxicity to cells led to the development of a new class of anti cancer drugs based on p-quinone.

    I went on in a bit too much detail there but hopefully you'll all find it an interesting read. None of that is actually needed for LC Chemistry but understanding why one is toxic and one isn't is better than "just knowing"!

    Absolutely brilliant! Thanks for that! What're you studying in college? Pharmacy? Chem science? That's A LOT of extra knowledge:P


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    #90
    partyatmygaff
    Registered Users Posts: 10,992 ✭✭✭✭partyatmygaff


    ei.sderob wrote: »
    Absolutely brilliant! Thanks for that! What're you studying in college? Pharmacy? Chem science? That's A LOT of extra knowledge:P
    You're spot on with your guess. Pharmacy at the moment :D


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    #91
    finality
    Registered Users Posts: 1,763 ✭✭✭finality


    That was really interesting, partyatmygaff. Thanks :)


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