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AS chemistry - post here if need help watch

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    anyone with problems, plz post here. im very willing to help.
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    can u help with a2 questions too?

    anyways my question is AS. why do you have to add sulphuric acid to water and not water to acid?
    thanx
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    (Original post by scarlet ibis)
    can u help with a2 questions too?

    anyways my question is AS. why do you have to add sulphuric acid to water and not water to acid?
    thanx
    I dont see what you mean..

    An acid has to be aqueous to be an acid - it is not acidic in soild form as this doesnt mean anything.

    You can post any level questions anywhere on the board as there is a wide range of experience and education level.
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    Basiacally Ive Failed Already
    Doing Ocr Salters Got 1 Mark Of A D In Jan They Took 10% Off When Weighting *******s!
    Now Im Gonna Fail
    Got An A In C/wk
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    (Original post by scarlet ibis)
    can u help with a2 questions too?

    anyways my question is AS. why do you have to add sulphuric acid to water and not water to acid?
    thanx
    prevent splashing urself back? adding acid to water is safer cuz u can control the amount of acid i guess...
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    sulphuric acid + water is a very exothermic reaction, and apparantly adding the water to the acid is more dangerous than the other way around, but i don't know why!
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    (Original post by scarlet ibis)
    sulphuric acid + water is a very exothermic reaction, and apparantly adding the water to the acid is more dangerous than the other way around, but i don't know why!
    this probably wont come up on the exam... y dont u ask sth that is on the syllabus?
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    (Original post by scarlet ibis)
    sulphuric acid + water is a very exothermic reaction, and apparantly adding the water to the acid is more dangerous than the other way around, but i don't know why!
    you always add acid to water as is less likely to spit on you, what board are you doing?
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    edexcel. what d'you mean, less likely to spit on you? wouldn't it spit whichever order you added it in?
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    If you add water to excess H(2)SO(4) (l) you are effectively making the most concentrated acid you could possibly make, and also it is extremely exothermic. If you do it the other way round, adding H(2)SO(4) (l) to an excess of water the reaction will still be very exothermic but the acid will be a lot more diluted.

    The way to avoid the exothermic-ness of the reaction is to add the H(2)SO(4) (l) to about 98% acid and 2% water so that the enthalpy change is not so large.

    However in real life they convert it to olium and then dissolve that in water I think, which is a lot safer. But we don't need to know this. :confused:
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    (Original post by scarlet ibis)
    edexcel. what d'you mean, less likely to spit on you? wouldn't it spit whichever order you added it in?
    man... ask sth more specific on the syllabus
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    btw does anyone have any sites for getting AS chem past papers for edexcel?
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    What does sth mean? you always say it but I never know what it means :confused:

    1. Write the equations for the thermal decompositions of LiNO3 and NaNO3 (4)
    2. State the products and conditions of the reaction between propene and hydrogen. (3)
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    (Original post by mik1a)
    What does sth mean? you always say it but I never know what it means :confused:

    1. Write the equations for the thermal decompositions of LiNO3 and NaNO3 (4)
    2. State the products and conditions of the reaction between propene and hydrogen. (3)
    sth = something?? -_-'

    1)LiNO3 --> Li2O + NO2 + O2
    NaNO3 --> NaNO2 + O2

    2) propane, around 400k, 500kPa, catalyst like nickel, platinum or palladium? should be finely divided to speed up reaction.
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    oopz didnt balance those equations... u do it
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    (Original post by z!D4N)
    sth = something?? -_-'

    1)LiNO3 --> Li2O + NO2 + O2
    NaNO3 --> NaNO2 + O2

    2) propane, around 400k, 500kPa, catalyst like nickel, platinum or palladium? should be finely divided to speed up reaction.
    1) 4LiNO3 ---> 2Li(2)O + 2NO(2) + O2
    2NaNO3 ----> 2NaNO(2) + O2

    Propane yep, We are taught 150*C which is 423K, Ni catalyst. Well done.
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    uhh well, you got any A2 Chemistry Markschemes for OCR?
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    btw for AS chem edexcel, do we need to know how to distinguish between carboxylic acid, aldehydes and ketones?
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    4LiNo3 ...> 2Li2O +4No2 +02
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    (Original post by scarlet ibis)
    can u help with a2 questions too?

    anyways my question is AS. why do you have to add sulphuric acid to water and not water to acid?
    thanx
    Your doing this wrong. Get half a beaker of sugar and put a drop of water in. The add some conc. H2SO4.

    MB
 
 
 
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