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OCR AS Salters Chemistry F332 - Wednesday 23rd May 2012 1:30pm

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    (Original post by dongonaeatu)
    that is wrong

    you should know hydrogen bonding is the stronger intermolecular bond
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    (Original post by sharon800)
    for the first bit i think i got 6.52 * 10^-4 or was that for different question?
    I think that's for another question. But SimpleGirl is right, although i can't remember the exact figures, but that is what i did.
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    (Original post by SimpleGirl)
    I wrote addition too and have been thinking that's correct but I just realised that it can't be addition polymerisation because it wasn't two of the same monomer that combined to form the product, was it?
    So I think Sharon's right, it was most likely co-polymerisation.
    It can be an addition reaction without being addition polymerisation (unless of course you wrote the latter); it wasn't a long chain so i doubt it's regarded as a polymer. Because as i recall it asked what sort of reaction they tried to achieve, not what sort of polymerisation.
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    (Original post by Crushy10)
    It can be an addition reaction without being addition polymerisation (unless of course you wrote the latter); it wasn't a long chain so i doubt it's regarded as a polymer. Because as i recall it asked what sort of reaction they tried to achieve, not what sort of polymerisation.
    Hm, yeah, you're right.

    I don't know, I guess we'll just have to wait and see :dontknow:
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    . a) What are the functional groups present in the molecules? (2)
    A. Alkene, ketone (carbonyl)
    b) What is the molecular formula of the molecule? (2)
    A. C15H22O
    c) If bromine water is added, what will the colour change be? (2)
    A. brown/red/orange to colourless
    d) write the equation of the reaction will excess bromine water. Use the molecular formula from a) (2)
    A. C15H220 + 2Br2 = C15H22O(Br2)2
    e) What type of reaction is this? (2)
    A. Electrophilic addition
    g) Bromine reacts with Silver nitrate, what would the student see? (2)
    A. cream precipitate
    2. What type of alcohol does this molecule contain? (1)
    A. Tertiary
    b) Explain your answer (1)
    A. The carbon atom to which the -OH group is attached is attached to three other carbon atoms/ the carbon which the OH group is bonded to is bonded to no hydrogen atoms
    c) What is the strongest bond that this molecule can form? (1)
    A. Hydrogen bonding
    d) Draw an OH radical, include the outer shell only. (1)
    A. One 'dot' and 'cross' forming a bond between O and H
    Then 5 more e- on the O, one on its own
    e) What type of reaction produces the hydroxyl radical? (1)
    A. Homolytic fission
    f) Producing an alcohol from an alkene when water is added. State the reagents and conditions required. (2)
    A. Phosphoric acid catalyst (allows sulphuric acid)
    High temperatures and pressures / 300C and 60atm
    g) Shows two compounds. A contained tertiary alcohols, B contained a primary alcohol. Describe the colour changes when potassium dichromate is added and explain this in terms of the types of alcohol. (5) (1 mark for QWC?)
    A. A cannot be oxidised by potassium dichromate as it contains no H on the C atom to which the -OH group is attached.
    Thus the colour will not change, it will remain orange
    B can be oxidised as it is a primary alcohol and so does contain H atoms on the C to which the -OH group is attached
    B will produce a colour change of orange to green and a carboxylic acid will be produced.

    3. a) Name the compound CFl3CCl2H (2)
    A. 2,2 - dichloro, 1,1,1 - trifluroethene
    b) Why is compound A less expensive? (1)
    A. Some wrote that it contains no halogen atoms, and thus is less expensive to transport, halogens are costly to extract e.g. electrolysis
    c) Why can this compound not be used as a cleaning agent (1)
    A. Some wrote because it does not contain chlorine and so will not kill bacteria
    Others quoted a fact from the table provided
    d) Explain why CFCs are not broken down in the troposphere and explain how CFCs deplete ozone
    (5)
    A. The C-F bond is too strong to be broken in the troposphere (1)
    In the stratosphere the C-F bond breaks in the presence of high energy (1) UV radiation (1), by photo-dissociation (1?)
    This forms Fluorine radicals (1)
    Which catalyse ozone break down (1)
    ii) Why is ozone a benefit? (3)
    A. Ozone absorbs high energy (1) (can also quote specific v) UV radiation (1) which would cause skin cancer (1)


    e) Label the partial charges on a CCl3F molecule (1)
    A. delta positive on C, delta negative on all chlorine and fluorine atoms
    g) explain what these partial charges are (2)
    A. The partial charges show the differences in electronegativity values
    Chlorine and Fluorine have a greater share of the e- and so have a partial negative charge
    C has less of the share of electrons and so has a partial positive charge, change in electron density within bond
    h) Draw the 3-D shape of the molecule. (1)
    A. Should include a tetrahedral shape with a wedge and a dotted line
    i) based on g and h, is this molecule polar? (2)
    A. This molecule is not polar
    j) What are the oxidation states of Sulphur and was it Oxygen? (3)
    Sulphur was +4 to +6, Bromine was 0 to -1
    k) what is the formula of the reducing agent? (2)
    S as it is itself oxidised and reduces oxygen
    l) Name one agricultural source of methane (1)
    A. Rice paddies/cattle farming/ mark scheme will include varied options
    m) explain how increased conc. of methane are linked to global warming (2)
    A. More methane molecules means more IR is absorbed (1) which increases the kinetic energy of the molecules and thus the temperature is increased (1)
    4. Explain dynamic equilibrium (2)
    A. Rate of forward reaction equals rate of reverse reaction (1) in a closed system/ conc. of reactants and products stay the same (1)
    b) Why use nano something or other (2)
    A. Provides a larger surface area for reacting particles to react. Thus there will be more frequent collisions, increasing the ROR
    c) What is activation enthalpy (2)
    A. The minimum energy required for colliding particles to react successfully. The energy needed to overcome the activation enthalpy barrier etc.
    d) Effect of increased pressure on rate of reaction (3)
    A. Increasing the pressure means the reacting particles are in closer proximity to each other. There will be more collisions. The rate of reaction will increase
    e) Increased pressure on yield (3)
    A. Position of equilibrium will shift to the .... (what side it was) / side with fewest gas molecules. So there will be increase/decrease in yield
    e) Increased temperature on yield (3)
    A. POE will shift to the right as the reaction favours the endothermic reaction.So the yield of products will increase
    f) How many more times abundant is oxygen compared to methane? (2)
    A. Oxygen was 21% methane was 0.00018%
    11677
    5. what is an addition polymer? give an example from the article but not poly(ethene) (3)
    A. Many different answers...
    I wrote along the lines of.... a large chain made up of many monomers added together
    Could of included any polymer from the article, e.g. poly(propene)
    b) Infrared spectroscopy (4)
    I believe you had to discuss how the bonds absorb specific frequencies of IR
    c) what would the people expect if reaction 2.1 had occurred? (2)
    I believe you had to quote the absorptions of the functional groups
    d) What is an initiation reaction? (1)
    A. Produces radicals. There are no radicals at the start of this stage but there are at the end of the stage
    e) What does a single headed arrow show? (1)
    A. The movement of one electron
    F) Find an example of this reaction (Termination) from the advanced notice (1)
    A. Draw thingy Ra.
    g) What type of reaction was the last radical reaction (1)
    A. Termination
    h) The I.B's question. How they are formed, how the structure link to strength of I.Bs (7)
    A. Electrons are constantly moving
    This creates an uneven distribution of charge
    This creates an instantaneous dipole (1?)
    Which induces a dipole in a neighbouring molecule
    The two are then attracted

    HDPE is un-branched and so has a larger molecular surface area
    The chains can pack more closely resulting in stronger I.Bs as they are closer together
    Thus, HDPE can whithstand more force than LDPE as it takes more energy to break the bonds

    Plank’s constant questions (5)
    Titration Questions (4)
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    This is only 94/100 of the marks, so 6 more still uo for grabs
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    one question missing is one of the pre release ones "what type of reaction is this (figure 1)" or something, was it addition reaction?
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    (Original post by xxZazxx)
    one question missing is one of the pre release ones "what type of reaction is this (figure 1)" or something, was it addition reaction?
    I put electrophilic addition.. because of the double bond.. i'm not 100% sure though xx
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    im SURE the molecule was polar..
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    (Original post by FuLLuPMepOrtION)
    im SURE the molecule was polar..
    It was we went through the paper with my teacher, and he basically gave us a round about mark scheme, so if you would like to know any of the answers, let me know
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    (Original post by ashleighlg)
    It was we went through the paper with my teacher, and he basically gave us a round about mark scheme, so if you would like to know any of the answers, let me know
    Question in the pre-release section: What type of reaction is shown in figure 1?
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    (Original post by SimpleGirl)
    Question in the pre-release section: What type of reaction is shown in figure 1?
    Addition
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    (Original post by ashleighlg)
    It was we went through the paper with my teacher, and he basically gave us a round about mark scheme, so if you would like to know any of the answers, let me know
    What did he say was the reducing agent? S or SO2
    And for the 4 mark spectroscopy question, was the answer anything to do with the molecules' bonds having fixed vibrational energy levels?
    Thanks
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    (Original post by Username_valid)
    What did he say was the reducing agent? S or SO2
    And for the 4 mark spectroscopy question, was the answer anything to do with the molecules' bonds having fixed vibrational energy levels?
    Thanks
    He said sulfur Erm no he said it was more about the actual technique and then about the fingerprint region
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    (Original post by ECRUJUMPER)
    Didn't know where to post this, but I made this PowerPoint for the Exam tomorrow and thought someone else might find it helpful too. It covers almost everything on the Atmosphere side of the course.
    Do you have on of these for A2 chemistry
    Thanks
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    (Original post by ashleighlg)
    He said sulfur Erm no he said it was more about the actual technique and then about the fingerprint region
    Ah OK thanks, I put down sulfur but must of got the spectroscopy all wrong. Oh well just have to wait and see now
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    (Original post by Username_valid)
    Ah OK thanks, I put down sulfur but must of got the spectroscopy all wrong. Oh well just have to wait and see now
    Yeah I same, but my teacher said that you might get some marks for putting certain keywords, or for a BOD mark
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    I also went through it with my teacher and he said that the molecule had no overall dipole. He also said that at A level this is the expected answer
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    (Original post by matt1107)
    . a) What are the functional groups present in the molecules? (2)
    A. Alkene, ketone (carbonyl)
    b) What is the molecular formula of the molecule? (2)
    A. C15H22O
    c) If bromine water is added, what will the colour change be? (2)
    A. brown/red/orange to colourless
    d) write the equation of the reaction will excess bromine water. Use the molecular formula from a) (2)
    A. C15H220 + 2Br2 = C15H22O(Br2)2
    e) What type of reaction is this? (2)
    A. Electrophilic addition
    g) Bromine reacts with Silver nitrate, what would the student see? (2)
    A. cream precipitate
    2. What type of alcohol does this molecule contain? (1)
    A. Tertiary
    b) Explain your answer (1)
    A. The carbon atom to which the -OH group is attached is attached to three other carbon atoms/ the carbon which the OH group is bonded to is bonded to no hydrogen atoms
    c) What is the strongest bond that this molecule can form? (1)
    A. Hydrogen bonding
    d) Draw an OH radical, include the outer shell only. (1)
    A. One 'dot' and 'cross' forming a bond between O and H
    Then 5 more e- on the O, one on its own
    e) What type of reaction produces the hydroxyl radical? (1)
    A. Homolytic fission
    f) Producing an alcohol from an alkene when water is added. State the reagents and conditions required. (2)
    A. Phosphoric acid catalyst (allows sulphuric acid)
    High temperatures and pressures / 300C and 60atm
    g) Shows two compounds. A contained tertiary alcohols, B contained a primary alcohol. Describe the colour changes when potassium dichromate is added and explain this in terms of the types of alcohol. (5) (1 mark for QWC?)
    A. A cannot be oxidised by potassium dichromate as it contains no H on the C atom to which the -OH group is attached.
    Thus the colour will not change, it will remain orange
    B can be oxidised as it is a primary alcohol and so does contain H atoms on the C to which the -OH group is attached
    B will produce a colour change of orange to green and a carboxylic acid will be produced.

    3. a) Name the compound CFl3CCl2H (2)
    A. 2,2 - dichloro, 1,1,1 - trifluroethene
    b) Why is compound A less expensive? (1)
    A. Some wrote that it contains no halogen atoms, and thus is less expensive to transport, halogens are costly to extract e.g. electrolysis
    c) Why can this compound not be used as a cleaning agent (1)
    A. Some wrote because it does not contain chlorine and so will not kill bacteria
    Others quoted a fact from the table provided
    d) Explain why CFCs are not broken down in the troposphere and explain how CFCs deplete ozone
    (5)
    A. The C-F bond is too strong to be broken in the troposphere (1)
    In the stratosphere the C-F bond breaks in the presence of high energy (1) UV radiation (1), by photo-dissociation (1?)
    This forms Fluorine radicals (1)
    Which catalyse ozone break down (1)
    ii) Why is ozone a benefit? (3)
    A. Ozone absorbs high energy (1) (can also quote specific v) UV radiation (1) which would cause skin cancer (1)


    e) Label the partial charges on a CCl3F molecule (1)
    A. delta positive on C, delta negative on all chlorine and fluorine atoms
    g) explain what these partial charges are (2)
    A. The partial charges show the differences in electronegativity values
    Chlorine and Fluorine have a greater share of the e- and so have a partial negative charge
    C has less of the share of electrons and so has a partial positive charge, change in electron density within bond
    h) Draw the 3-D shape of the molecule. (1)
    A. Should include a tetrahedral shape with a wedge and a dotted line
    i) based on g and h, is this molecule polar? (2)
    A. This molecule is not polar
    j) What are the oxidation states of Sulphur and was it Oxygen? (3)
    Sulphur was +4 to +6, Bromine was 0 to -1
    k) what is the formula of the reducing agent? (2)
    S as it is itself oxidised and reduces oxygen
    l) Name one agricultural source of methane (1)
    A. Rice paddies/cattle farming/ mark scheme will include varied options
    m) explain how increased conc. of methane are linked to global warming (2)
    A. More methane molecules means more IR is absorbed (1) which increases the kinetic energy of the molecules and thus the temperature is increased (1)
    4. Explain dynamic equilibrium (2)
    A. Rate of forward reaction equals rate of reverse reaction (1) in a closed system/ conc. of reactants and products stay the same (1)
    b) Why use nano something or other (2)
    A. Provides a larger surface area for reacting particles to react. Thus there will be more frequent collisions, increasing the ROR
    c) What is activation enthalpy (2)
    A. The minimum energy required for colliding particles to react successfully. The energy needed to overcome the activation enthalpy barrier etc.
    d) Effect of increased pressure on rate of reaction (3)
    A. Increasing the pressure means the reacting particles are in closer proximity to each other. There will be more collisions. The rate of reaction will increase
    e) Increased pressure on yield (3)
    A. Position of equilibrium will shift to the .... (what side it was) / side with fewest gas molecules. So there will be increase/decrease in yield
    e) Increased temperature on yield (3)
    A. POE will shift to the right as the reaction favours the endothermic reaction.So the yield of products will increase
    f) How many more times abundant is oxygen compared to methane? (2)
    A. Oxygen was 21% methane was 0.00018%
    11677
    5. what is an addition polymer? give an example from the article but not poly(ethene) (3)
    A. Many different answers...
    I wrote along the lines of.... a large chain made up of many monomers added together
    Could of included any polymer from the article, e.g. poly(propene)
    b) Infrared spectroscopy (4)
    I believe you had to discuss how the bonds absorb specific frequencies of IR
    c) what would the people expect if reaction 2.1 had occurred? (2)
    I believe you had to quote the absorptions of the functional groups
    d) What is an initiation reaction? (1)
    A. Produces radicals. There are no radicals at the start of this stage but there are at the end of the stage
    e) What does a single headed arrow show? (1)
    A. The movement of one electron
    F) Find an example of this reaction (Termination) from the advanced notice (1)
    A. Draw thingy Ra.
    g) What type of reaction was the last radical reaction (1)
    A. Termination
    h) The I.B's question. How they are formed, how the structure link to strength of I.Bs (7)
    A. Electrons are constantly moving
    This creates an uneven distribution of charge
    This creates an instantaneous dipole (1?)
    Which induces a dipole in a neighbouring molecule
    The two are then attracted

    HDPE is un-branched and so has a larger molecular surface area
    The chains can pack more closely resulting in stronger I.Bs as they are closer together
    Thus, HDPE can whithstand more force than LDPE as it takes more energy to break the bonds

    Plank’s constant questions (5)
    Titration Questions (4)
    Thanks for just copying MY mark scheme from the previous page, brilliant. (Y)
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    I made some changes because they were wrong, and added a few questions =D

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