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    (Original post by Sumaiyya1999)
    This isnt an approximation our school makes us give the unit 1 in jan and unit 2 and 3 in june and i got a B in unit 1 in jan
    Oh! I thought that you were taking all the AS papers together. Cheer up! Mistakes happen. You can always retake the paper if the mark is not satisfactory. You can also ask here if you have any doubts !!
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    (Original post by pondsteps)
    can someone pls explain this!!
    plus arent ethanol and ethanal meant to have the same molar mass or am i wrong??
    Ethanal: CH3CHO

    Ethanol : CH3CH2OH

    Fragment produced by ethanal that is produced by ethanol is CHO+ or HCO+ because the CH3 is common in both.
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    (Original post by Sandy_Vega30)
    Oh yeah, well if I were to answer this question I would choose A because pressure has no effect on an equilibrium that has equal moles on both sides. But I don't know why the answer is D. Give me sometime, I'll ask my teacher and let you know soon
    As for the tips, especially the one markers. Always answer in context to the question. Try and understand or better, visualize the question. Any one marker following that question would probably sound like : Why was so and so used to blah blah blah? In this case, try and analyse the experiment. This may give you lots of sensible points. Try learning all the diagrams for distillation etc. Good luck!
    i think it is becoz wen a coloured gas is compressed to a small volume da normal colur of gas mixture darkens
    n i think it has nothn to do wit equilibrium as if it depends on it da answer would be no change
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    (Original post by Sandy_Vega30)
    Ethanal: CH3CHO

    Ethanol : CH3CH2OH

    Fragment produced by ethanal that is produced by ethanol is CHO+ or HCO+ because the CH3 is common in both.
    i dont think ethanol can produce a COH+fragment
    CH3+ fragments can be produced by both ethanol and ethanaltherfore the remaining fragment in ethanal will be COH+ and in ethanol CH2OH+
    another example fr differnet fragments r ethanal - C2H3O+
    ethanol C2H5O+
    (am i ryt?)
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    (Original post by saitama kun)
    i dont think ethanol can produce a COH+fragment
    CH3+ fragments can be produced by both ethanol and ethanaltherfore the remaining fragment in ethanal will be COH+ and in ethanol CH2OH+
    another example fr differnet fragments r ethanal - C2H3O+
    ethanol C2H5O+
    (am i ryt?)
    Yup you're right. I guess Sandy_Vega30 mistyped the last sentence she wrote. Probably meant "the fragment in ethanal that is not present in ethanol in HCO+"
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    (Original post by Arzam45)
    Yup you're right. I guess Sandy_Vega30 mistyped the last sentence she wrote. Probably meant "the fragment in ethanal that is not present in ethanol in HCO+"
    Yes I did. Sorry.
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    (Original post by Sumaiyya1999)
    This isnt an approximation our school makes us give the unit 1 in jan and unit 2 and 3 in june and i got a B in unit 1 in jan
    Well the bundary for A was too high
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    (Original post by Sandy_Vega30)
    Hey guys! This is the official thread for Chem Unit 2. How is your revision?
    I think you've got the paper reference wrong in the thread title. if im not mistaken its WCH02/01
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    (Original post by IAROX15)
    I think you've got the paper reference wrong in the thread title. if im not mistaken its WCH02/01
    I noticed that too! I tried editing it. But I don't know how. Any suggestions?
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    Does anyone have decent notes for this paper ??

    Maybe I am asking too much of you Sandy, but did you ask your teacher about that equilibrium question I posted earlier ? Clarifying that would be great.
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    (Original post by omar5478)
    Does anyone have decent notes for this paper ??

    Maybe I am asking too much of you Sandy, but did you ask your teacher about that equilibrium question I posted earlier ? Clarifying that would be great.
    I did ask him about it. He told me that the answer is D because of the word 'immediately'. i.e The equilibrium is not restored immediately after the increase in pressure so the immediate change would be to make more products hence it turns more dark purple.

    He also told me that if the word 'immediately' was not there, then it would mean that the equilibrium is already restored. Only then the answer would be NO CHANGE.

    Hope you got it. Sorry for the delay.
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    (Original post by Sandy_Vega30)
    I did ask him about it. He told me that the answer is D because of the word 'immediately'. i.e The equilibrium is not restored immediately after the increase in pressure so the immediate change would be to make more products hence it turns more dark purple.

    He also told me that if the word 'immediately' was not there, then it would mean that the equilibrium is already restored. Only then the answer would be NO CHANGE.

    Hope you got it. Sorry for the delay.
    Thank you !!!
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    Does anyone know how to answer the very last question in jan 2016 ?? Basically it said that 0.5 moles of chlorine were bubbled into a mixture containing 0.66 moles of sodium Iodine and 0.66 moles of sodium Bromine, and asked to calculate the number of Iodine and bromine produced. The answer was that 0.33 of iodine was produced and 0.167 of bromine was produced. Although I know that Iodine has a higher reducing power than bromine and thus more Iodine would be produced, I don't know how to calculate this.
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    (Original post by omar5478)
    Does anyone know how to answer the very last question in jan 2016 ?? Basically it said that 0.5 moles of chlorine were bubbled into a mixture containing 0.66 moles of sodium Iodine and 0.66 moles of sodium Bromine, and asked to calculate the number of Iodine and bromine produced. The answer was that 0.33 of iodine was produced and 0.167 of bromine was produced. Although I know that Iodine has a higher reducing power than bromine and thus more Iodine would be produced, I don't know how to calculate this.
    Help, please !!!
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    (Original post by sllinares)
    Does anyone have useful revision resources for chem unit 2?? Thanks

    https://chemrevise.org/revision-guides/
    for great notes
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    guys does any one have any tips on green chem?
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    Posted from TSR Mobile
    Physics and math tutor has spme amazing notes
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    I've got a question, what volume of 0.200mol/dm^3 potassium sulfate solution is required to make, by dilution with water, 1 dm^3 of a solution with a potassium ion concentration of 0.1 mol/dm^3?

    A 100 cm^3
    B 250 cm^3
    C 400 cm^3
    D 500 cm^3

    Posted from TSR Mobile
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    (Original post by Willandy123)
    I've got a question, what volume of 0.200mol/dm^3 potassium sulfate solution is required to make, by dilution with water, 1 dm^3 of a solution with a potassium ion concentration of 0.1 mol/dm^3?

    A 100 cm^3
    B 250 cm^3
    C 400 cm^3
    D 500 cm^3

    Posted from TSR Mobile
    Moles of K ions needed is = concentration * volume which is 0.1*1 = 0.1 moles

    Potassium sulfate is K2SO4, so each mole of it produces two moles of K ions. This means that 0.05 moles of potassium sulfate produces the required amount of potassium ions.

    Volume = moles/concentration = 0.05/0.2 = 0.25 dm^3 = 250 cm^3
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    can anyone please explain the mechanism of Ammonia reacting with Haloalkanes?
 
 
 
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