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Edexcel A2 Chemistry Exams -6CH04 (14th June) and 6CH05 (22nd June) Discussion Thread Watch

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    (Original post by Whizbox)
    I'm willing to try and see what I remember, but I need help with the topics
    I remember 13 questions but I'm not saying the answers are right they're just what I put! Answers in brackets
    Multiple choice:
    Dont remember the order but:

    What kind of reaction is this (D, transesterification)
    What is the product of transesterification of palm oil (D)
    How to increase yield of equilibrium: (B, decrease temperature and pressure)
    a) What similarities are there between the two mechanisms? (?)
    b) (only one mechanism forms a racemic mixture)
    Gas chromatography:
    a) (Nitrogen)
    b) (how it interacts with the stationary phase)
    polyester: (A, the one with C=O on either side of the benzene)
    Iodine equilibrium (water should be on bottom, and have a lower [iodine])

    W: ketone
    X: aldehyde
    Y: primary alcohol
    Z: secondary alcohol
    Which is optically active (?)
    Which forms structural isomers (?)
    Positive iodoform test result (?)
    Which reacts with 2,4-dnph
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    Guys was it effect of temperature increase or decrease?????
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    (Original post by lfcrules)
    I think doing ln (1/time ) on the y axis is ok isnt it as it proprtional to rate . Swear ive seen that in a past paper???
    i don't know...but why would you even do that when they clearly gave you an equation that works??? :confused:
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    (Original post by Don Pedro K.)
    Guys was it effect of temperature increase or decrease?????
    I'm afraid it was the effect of temperature increase.
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    I couldnt actually get the answer for the K value using the total entropy = rlnK

    Surely you could only arrange for ln K, not K and otherwise you would have to use A2 maths skills to do it, which shouldnt be allowed
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    (Original post by setarcos)
    I'm afraid it was the effect of temperature increase.
    Well hot diggity. How many marks was that q?
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    please please please someone post the full unofficial mark scheme. put me out of my misery!!
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    (Original post by rachelmcarthur)
    I think it's pretty unfair that when you were given the lnK equation to rearrange you needed to know some A2 maths in order to work with ln. Lost that mark for sure.
    I agree, I even wasted a few precious seconds wondering how they expected non a level maths students to do that
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    (Original post by Don Pedro K.)
    Well hot diggity. How many marks was that q?
    It was 3 marks :\
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    (Original post by sayshay)
    I agree, I even wasted a few precious seconds wondering how they expected non a level maths students to do that
    Same
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    (Original post by setarcos)
    It was 3 marks :\
    Nice!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!
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    For the entropy assumption for when you increase temperature I wrote that there is no change in state of H2O so the H2O doesn't turn into a gas as this would increase the entropy of system. Is this correct?
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    I think I got a solid -100/90 ))))) lol.
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    (Original post by Don Pedro K.)
    Guys was it effect of temperature increase or decrease?????
    I am convinced that i am illiterate but to me it made sense that they used the word slightly for decrease because the dS total was quite small anyway so a large decrease in temperature would've meant that the dS surroundings would be too negative and dS total would've become negative...so they didn't want us to talk about dS total becoming negative and so they said just slight decrease.... but I wouldn't be surprised if it was increase either because I have a history of ****ing up my exams with illiteracy
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    umm ok i wrote something completely different.. it asked about how the entropy changes were consistent with the trend for group 2 hyroxides solubility. so i wrote that since the entropy change value for calcium hydroxide is more negative than that for ba(oh)2 the reaction with water is thermodynamically less feasible at room temp and so is less soluble than ba(oh)2. this is consistent with the trend bc hydroxides solubility increases down the group
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    (Original post by CLGC98)
    I couldnt actually get the answer for the K value using the total entropy = rlnK

    Surely you could only arrange for ln K, not K and otherwise you would have to use A2 maths skills to do it, which shouldnt be allowed
    totally agree, this was unfair. I put ln in the calculator and got a number along the lines of 1.03... and used that, only to come out of the exam with a friend say you had to know A2 maths to be able to rearrange it
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    (Original post by Don Pedro K.)
    Guys was it effect of temperature increase or decrease?????
    Increase
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    (Original post by dj3k)
    For the entropy assumption for when you increase temperature I wrote that there is no change in state of H2O so the H2O doesn't turn into a gas as this would increase the entropy of system. Is this correct?
    Assumption is that dH and dS system is unchanged
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    (Original post by C0balt)
    I am convinced that i am illiterate but to me it made sense that they used the word slightly for decrease because the dS total was quite small anyway so a large decrease in temperature would've meant that the dS surroundings would be too negative and dS total would've become negative...so they didn't want us to talk about dS total becoming negative and so they said just slight decrease.... but I wouldn't be surprised if it was increase either because I have a history of ****ing up my exams with illiteracy
    It was increase :/ I still interpreted it wrongly though and said delta S surroundings would become more negative even those it becomes less negative... Flipping hate this.
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    (Original post by Don Pedro K.)
    Nice!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!
    well FML lost 2 free marks lol
    (Original post by Aijazzhands)
    umm ok i wrote something completely different.. it asked about how the entropy changes were consistent with the trend for group 2 hyroxides solubility. so i wrote that since the entropy change value for calcium hydroxide is more negative than that for ba(oh)2 the reaction with water is thermodynamically less feasible at room temp and so is less soluble than ba(oh)2. this is consistent with the trend bc hydroxides solubility increases down the group
    i think thats about right
 
 
 
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