Join TSR now and get all your revision questions answeredSign up now
    Offline

    0
    ReputationRep:
    A compound which has major peaks with mass / charge ratio at 29, 57 and 58 in the
    mass spectrum could be

    A propanal, CH3CH2CHO.
    B propanone, CH3COCH3
    .C propan-1-ol, CH3CH2CH2OH.
    D propan-2-ol, CH3CH(OH)CH3.
    The answer is A but I can't for the love of god figure out why. Same thing for this Q
    A charged rod is held beside a stream of liquid coming from a burette. Which of the
    following liquids would NOT be significantly deflected?

    A H2O
    B CCl4
    C C2H5OH
    D C2H5Br

    Can you explain why the answer is B?
    Self studying here so I don't have a teacher to ask. Does it have anything to do with electronegativity difference between the molecules?
    Offline

    3
    ReputationRep:
    (Original post by Chinensis8)
    A compound which has major peaks with mass / charge ratio at 29, 57 and 58 in the
    mass spectrum could be

    A propanal, CH3CH2CHO.
    B propanone, CH3COCH3
    .C propan-1-ol, CH3CH2CH2OH.
    D propan-2-ol, CH3CH(OH)CH3.
    The answer is A but I can't for the love of god figure out why. Same thing for this Q
    A charged rod is held beside a stream of liquid coming from a burette. Which of the
    following liquids would NOT be significantly deflected?

    A H2O
    B CCl4
    C C2H5OH
    D C2H5Br

    Can you explain why the answer is B?
    Self studying here so I don't have a teacher to ask. Does it have anything to do with electronegativity difference between the molecules?
    For the second one, you need to think about which molecules are polar and which are not. You can draw a diagram of each if it helps and see where the polarity is. You should see that tetrachloromethane has negative bits all around and a positive bit in the middle. Because of that symmetrical distribution of charge (instead of having one end being delta positive and one end being delta negative), the molecule is non-polar so isn't really affected by charge.


    Posted from TSR Mobile
    • Community Assistant
    • Study Helper
    Offline

    14
    ReputationRep:
    (Original post by Chinensis8)
    A compound which has major peaks with mass / charge ratio at 29, 57 and 58 in the
    mass spectrum could be

    A propanal, CH3CH2CHO.
    B propanone, CH3COCH3
    .C propan-1-ol, CH3CH2CH2OH.
    D propan-2-ol, CH3CH(OH)CH3.
    The answer is A but I can't for the love of god figure out why.
    In MS questions remember that the molecular ion always gives a peak at the m/e of the relative molecular mass. This eliminates C and D

    There is a peak at m/e 29 suggesting [C2H5]+ or [CHO]+, both of which are present in A but not in B
    • Thread Starter
    Offline

    14
    ReputationRep:
    (Original post by lyricalvibe)
    I'm on it now for as! How did you do at As? How hard is the coursework?





    Bey be ignoring my pm :unimpressed:
    Ehh? You haven't PMed :lolwut:
    I don't ignore, I'm nice. Hehe i thought u blanked me
    • Welcome Squad
    Offline

    3
    ReputationRep:
    (Original post by Dinaa)
    Ehh? You haven't PMed :lolwut:
    I don't ignore, I'm nice. Hehe i thought u blanked me
    Shouldn't you be at sixth form? :teehee:

    I've got study leave for two weeks
    • Thread Starter
    Offline

    14
    ReputationRep:
    (Original post by zhang-liao)
    Shouldn't you be at sixth form? :teehee:

    I've got study leave for two weeks
    I have a doctors appointment about what I told you :cry2:
    I don't want to go school, ever :cry2:
    Lucky you!
    • Welcome Squad
    Offline

    3
    ReputationRep:
    (Original post by Dinaa)
    I have a doctors appointment about what I told you :cry2:
    I don't want to go school, ever :cry2:
    Lucky you!
    :console: Aaah I see. Get well soon

    Not so lucky if you've got 3 mocks this upcoming Wednesday straight after each other :lol:
    Offline

    3
    ooo 1 mock down 4 more to go
    Offline

    2
    ReputationRep:
    Hi everyone!, can someone please explain shapes of molecules, in bonding (chapter 3 unit 1 AQA AS chemistry) as in how would you know the angle in between the bonds and the name of the shape - as they are so many Thank you.
    Offline

    15
    ReputationRep:
    (Original post by Clovers)
    Hi everyone!, can someone please explain shapes of molecules, in bonding (chapter 3 unit 1 AQA AS chemistry) as in how would you know the angle in between the bonds and the name of the shape - as they are so many Thank you.
    Give an example and I'll show you how to work it out
    • Community Assistant
    • Study Helper
    Offline

    14
    ReputationRep:
    (Original post by Clovers)
    Hi everyone!, can someone please explain shapes of molecules, in bonding (chapter 3 unit 1 AQA AS chemistry) as in how would you know the angle in between the bonds and the name of the shape - as they are so many Thank you.
    Go through the shapes of molecules video in youtube Colourful Solutions. Then ask questions if you don't understand.
    • Community Assistant
    • Study Helper
    Offline

    14
    ReputationRep:
    (Original post by haemo)
    Hi,

    Someone has answered the second question for you, so I'll answer the first one.

    The spectrum (x axis) is labelled with increasing m/z, and the peak furthest to the right (with the highest m/z) is called the molecular ion peak.

    The peak is only called the molecular ion peak if the spectrum represents a molecule, not a single element.

    The molecular ion peak tells you the total mass (Mr) of the molecule, therefore from your answers (A-D) find which molecule has an Mr of 58, which is A.
    So has B!

    Someone has also answered this part for him ...
    Offline

    3
    ReputationRep:
    (Original post by De4thTh3K1d)
    Yup,

    I got my mock on Thursday I believe.
    you feeling prepared?

    Good luck
    Same to you i have mine next thursday though yay!
    And yeah I do , we have done 2 other mocks before this one so hopefully there wont be any masive uprises!
    Offline

    3
    ReputationRep:
    im in edexcel chemistry....have midterms for unit 1 soon and in class, have done 3 chap of unit 2.
    Offline

    3
    ReputationRep:
    (Original post by bukosaurus_rex)
    Hi!

    I got an A at AS which is quite easy to do if you know how to go about the exam, and the Advanced Notice Article, if you have any specific questions about this ask away.

    As for the coursework, it isn't too hard, the experiments aren't too demanding as long as you follow the instructions they give you and practice in a safe way you will be fine. They are almost always titrations, however you may have to do others.

    Always do readings to 2 decimal places or else you do lose a mark. Also make sure to draw your results table with units in the headings and when you draw a graph make sure the axes are labelled correctly with units as well and draw a line or curve of best fit.

    Really the hardest thing about the coursework is that your teacher will be doing the experiment and whatever results they get in their experiment you have to be within 0.1cm3 (for titrations) error margin in order to get 5/5 in that section. If you are 0.2cm3 out you get 4/5 and so on until 0.5cm3 where you get 1/5. So you really need to be within that higher boundary.

    Other than that, it is like the ISAs you may have done last year at GCSE, after the experiment you are given two papers to test your understanding

    The first will give you a small introduction to the experiment you have just done and will then ask you questions about it, such as "how many moles of a compound did you use?" and you have to work it out using the moles equation.

    They will ask you what the chemical equation or word equation is for your experiment, with titrations they will ask you what the unknown concentration of the compound is (this is what you do a titration for) so you have to know about ratios and the moles/concentration/volume equation. Also sometimes they ask about percentage error/ uncertainty is associated with one of the steps in your experiment for example your burette or pipette.

    The next is more contextual and will deal with the ideas you are working with in your experiment, but this is given to you some time after the first test.

    So for example if you worked with aqueous solutions of the elements chlorine, bromine and iodine and potassium chloride, potassium bromide and potassium iodide and cyclohexane; you may be asked what happens when a few drops of chlorine solution is added to an equal volume of cyclohexane and you may be asked why. So it is good to take note of what happened in your experiment, but your teacher should go through all the chemistry beforehand.

    So in all honesty with these just make sure your skills that are needed such as moles calculations, empirical formulae, even table and graph drawing are up to scratch.

    I hope this helped, if you are still unclear about anything, just ask me more questions, I'm happy to help.

    Thanks! This was really helpful!
    How's the A2 treating you?

    That part about being within 0.1 sounds terrifying :eek: and harsh! How many people got within 0.1 of the teacher value in your class roughly ?
    Side note, how hard is unit 2 compared to 1 in AS? Finished unit 1 with mock exam in december and the exam was fairly easy-as long as you knew what you were doing. Is it the same but more?
    Offline

    3
    ReputationRep:
    (Original post by BBeyond)
    ooo 1 mock down 4 more to go
    Was it chemistry how did it go?
    (Original post by Dinaa)
    Ehh? You haven't PMed :lolwut:
    I don't ignore, I'm nice. Hehe i thought u blanked me
    :lolwut::lolwut::lolwut:
    I replied on Christmas as like a present from me to you->my awesomeness :rolleyes:
    I thought you were busy or something :/

    Not sure whether to rereply or start a new message...
    Offline

    1
    ReputationRep:
    Hi... I'm new here... n desperately in need of help... can someone explain to me the difference between a RISK and a HAZARD? Also, what's the difference between cis-trans isomerism and E/Z nomenclature? I'm resitting for unit 1 and 2 papers after I flunked them... and i really don't wanna flunk them again! Thanks a bunch!
    Offline

    3
    (Original post by lyricalvibe)
    Was it chemistry how did it go?

    :lolwut::lolwut::lolwut:
    I replied on Christmas as like a present from me to you->my awesomeness :rolleyes:
    I thought you were busy or something :/

    Not sure whether to rereply or start a new message...
    nah economics, it was alright, chem tomorrow

    and #rekt by dina y0
    • Thread Starter
    Offline

    14
    ReputationRep:
    (Original post by lyricalvibe)
    Was it chemistry how did it go?

    :lolwut::lolwut::lolwut:
    I replied on Christmas as like a present from me to you->my awesomeness :rolleyes:
    I thought you were busy or something :/

    Not sure whether to rereply or start a new message...
    I'll check :hugs:
    Then I'll PM :sexface:
    • Thread Starter
    Offline

    14
    ReputationRep:
    (Original post by BBeyond)
    nah economics, it was alright, chem tomorrow

    and #rekt by dina y0
    You jelly? You know you want to be rekt by me :sexface:
 
 
 
Poll
Which Fantasy Franchise is the best?

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Quick reply
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.