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    (Original post by Enderbat1999)
    hard paper guys not good messed up on alot of the maths questions
    I thought it was easy except that question which doesn't make any sense.
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    did anyone do A2 1 CCEA this morning???

    Please tell me you thought it was brutal!!! I missed out like 4 questions - 10 marks in total!!!
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    (Original post by damian21kk)
    Why would there be a peak at 80 in mass spectrometry of Bromine? There are only two isotopes of bromine- 79 and 81 so why would there be peak at 80?
    Br2 with one Br79 one Br81 and a 2+ charge
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    Hey guys! Could anyone help me understand why the answer is A. Thanks in advance
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    (Original post by damian21kk)
    Why would there be a peak at 80 in mass spectrometry of Bromine? There are only two isotopes of bromine- 79 and 81 so why would there be peak at 80?
    I wrote that there is a Br2 molecule that is 79Br81Br so it adds up to 160. When it is being ionised it lost two electrons to form a 2+ ion and didn't fragment. So the m/z ratio is 160/2 which is 80
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    Hi guys am making a whattsapp group. please dm me. The whattsapp group is going to be for all chemistry examboards, as we all need to know the same things but just in different orders. PLease do DM me. thanks xx
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    Can someone please explain the highlighted question please? I looked into several textbooks couldn't find the answer to it.. It's for OCR B Salters course lol🙈


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    (Original post by FemaleBo55)
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    Can someone please explain the highlighted question please? I looked into several textbooks couldn't find the answer to it.. It's for OCR B Salters course lol🙈


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    Partial pressures of the different gases?
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    Can someone please tell me how to calculate the enthalpy change of combustion and the enthalpy change of formation when given a table? I always get confused from which calculation of enthalpies do I need to take away the sum of products from the sum of the reactants!!!!
    This is for OCR Chemistry A
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    (Original post by seph_muriel)
    Can someone please tell me how to calculate the enthalpy change of combustion and the enthalpy change of formation when given a table? I always get confused from which calculation of enthalpies do I need to take away the sum of products from the sum of the reactants!!!!
    This is for OCR Chemistry A
    For combustion you do reactants take away products. I rememeber this using the acronym CRAP or CAP ( combustion reactant takeaway products) CRAP sticks in my head aha

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    (Original post by mali473)
    For combustion you do reactants take away products. I rememeber this using the acronym CRAP or CAP ( combustion reactant takeaway products) CRAP sticks in my head aha

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    Thank you!!! The acronym is helpful too
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    can someone help me out on this question

    Give the formula of an organic compound that forms an alkaline buffer solution whenadded to a solution of ethylamine. The answer is CH3CH2NH3Cl and I'm not sure why
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    (Original post by seph_muriel)
    Thank you!!! The acronym is helpful too
    Whenever you see combustion just think 'crap'

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    (Original post by alow)
    Partial pressures of the different gases?
    Ohh, why would you need that???
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    (Original post by chrisgul)
    can someone help me out on this question

    Give the formula of an organic compound that forms an alkaline buffer solution whenadded to a solution of ethylamine. The answer is CH3CH2NH3Cl and I'm not sure why
    It's normally the salt of your amine so yeah ... I suppose it is because of acid and their salt forming buffers?! :yep:

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    (Original post by FemaleBo55)
    Ohh, why would you need that???
    Because then you'd know how much of each gas there is.
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    (Original post by voltz)
    For a titration, is the acid always in the burette or is the solution of unknown just always the base (in flask)?
    I think the standard solution (the one you know the concentration of) goes in the burette and the unknown goes in the flask. Don't quote me on that tho
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    organic question here !


    Methyl butanoate, C5H10O2, is an ester used in the food industry to give products the flavour of apples.
    structural formula: CH3C02CH2CH2CH3

    Including methyl butanoate, how many structural isomers are there of C5H10O2 that are esters?
    A) 6
    B) 8
    C) 9
    D) 10
    if anyone has doubts concerning the question ... let me know so I can explain the question in more detail....
    thank u
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    Am making a whattsapp group for f334 and f335 ocr b salters. if interested DM me.
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    I have absolutely no idea on how to answer this question:
    Suggest 2 reasons why standard enthalpy changes of combustion determined experimentally are less exothermic than the calculated theoretical values. (for 2 marks OCR Chemistry A)
 
 
 
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