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Chemistry c2 unit 2 aqa monday gcse 20th new spec watch

  • View Poll Results: Six Mark Question
    Making Soluble Salts
    23.53%
    Making Insoluble Salts
    20.59%
    Electrolysis
    26.47%
    Electroplating
    17.65%
    Rates of Reaction
    20.59%
    Properties of ionic compounds
    23.53%
    Nanoparticles
    35.29%
    Mass Spectrometry
    14.71%
    Gas Chromatography
    17.65%
    Other
    26.47%

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    (Original post by sa97)
    What would be the points for a 6-mark insoluble salt making question?

    1) Mix ionic substances in solution
    2) Filter/wash/dry precipitate to obtain salt.

    Is there anything else??

    Also what kind of things would they look for in a 6-mark electrolysis question?
    Last year had a 6 marker on making salts. They wanted you to describe the steps you would take in an experiment to create a salt. E.g using universal indicator, stirring and bunsen burners
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    (Original post by sa97)
    What would be the points for a 6-mark insoluble salt making question?

    1) Mix ionic substances in solution
    2) Filter/wash/dry precipitate to obtain salt.

    Is there anything else??

    Also what kind of things would they look for in a 6-mark electrolysis question?
    Sort of points you could get in for soluble salt:

    An Insoluble salt will not dissolve in solution, so the salt is formed as a precipitate. To Achieve Salt X (they'll name a salt in the question) you'll need to mix solution Y and Z together (names dependant on the salt you're trying to make). To obtain the precipitate you use a filter. The salt should then be washed with distilled water to remove the other soluble product. Finally, the salt can be dried in an oven.

    That could be enough for six marks.

    Points for electrolysis:

    Question, describe the electrolysis of Brine and how its products can be used.

    Brine is made up of sodium chloride and water. Chlorine moves towards the anode where is gives up an electron to form chlorine gas- insert relevant half equation. Chlorine gas can be used in the production of bleaches and plastics.

    Hydrogen moves towards the cathode where it gains an electron to form hydrogen gas- insert relevant half equation. Hydrogen forms at the cathode rather than sodium as it is lower in the reactivity series (this is to do with electrode potential, essentially hydrogen is lower down in the reactivity series so it will be reduced and gain electrons rather than something higher up), Hydrogen gas can be used in Hydrogen fuel cells and in modified combustion engines.

    A solution of Sodium Hydroxide is left, which is a useful component in making chemicals like soaps.

    Hope this helps
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    (Original post by Elm Tree)
    Last year had a 6 marker on making salts. They wanted you to describe the steps you would take in an experiment to create a salt. E.g using universal indicator, stirring and bunsen burners
    Careful! That question was on soluble salts and not insoluble salts. Very Big difference in terms of production, if you cant remember i suggest you go back and revise...
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    (Original post by sammann123)
    Careful! That question was on soluble salts and not insoluble salts. Very Big difference in terms of production, if you cant remember i suggest you go back and revise...
    :lol:
    You're right I need to brush up on how to make in/soluble salts. For some reason, I just can't seem to memorise it.. I'm fine with everything else though.
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    (Original post by Elm Tree)
    Last year had a 6 marker on making salts. They wanted you to describe the steps you would take in an experiment to create a salt. E.g using universal indicator, stirring and bunsen burners
    That was to make soluble salts, there are much fewer you could say for making insoluble ones, thanks for reminding me anyway.
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    (Original post by sammann123)
    Sort of points you could get in for soluble salt:

    An Insoluble salt will not dissolve in solution, so the salt is formed as a precipitate. To Achieve Salt X (they'll name a salt in the question) you'll need to mix solution Y and Z together (names dependant on the salt you're trying to make). To obtain the precipitate you use a filter. The salt should then be washed with distilled water to remove the other soluble product. Finally, the salt can be dried in an oven.

    That could be enough for six marks.

    Points for electrolysis:

    Question, describe the electrolysis of Brine and how its products can be used.

    Brine is made up of sodium chloride and water. Chlorine moves towards the anode where is gives up an electron to form chlorine gas- insert relevant half equation. Chlorine gas can be used in the production of bleaches and plastics.

    Hydrogen moves towards the cathode where it gains an electron to form hydrogen gas- insert relevant half equation. Hydrogen forms at the cathode rather than sodium as it is lower in the reactivity series (this is to do with electrode potential, essentially hydrogen is lower down in the reactivity series so it will be reduced and gain electrons rather than something higher up), Hydrogen gas can be used in Hydrogen fuel cells and in modified combustion engines.

    A solution of Sodium Hydroxide is left, which is a useful component in making chemicals like soaps.

    Hope this helps
    Thanks alot! Please correct me if I'm wrong but for electrolysis of brine, the half equations are:

    At negative electrode:
    2H+ + 2e- --> H2

    At positive electrode
    2Cl- --> Cl2 + 2e-

    The remaining OH- and Na+ ions which do not form at any electrode bond to form NaOH.
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    (Original post by Elm Tree)
    :lol:
    You're right I need to brush up on how to make in/soluble salts. For some reason, I just can't seem to memorise it.. I'm fine with everything else though.
    It's relatively simple once you get the main principles down!

    Insoluble:

    Acid+Metal>Salt+Hydrogen
    Simply add excess metal until all has been used up, then filter metal off and crystallise salt.
    Acid+Base>Salt+Water
    Add excess base until all has been used up, then filter base off and crystallise salt.
    Acid+Alkali>Salt+Water
    This is a little more complicated, and I suggest you learn titration procedure, despite the fact its not officially on the spec it essentially links the information that they tell you in the text book together. In my text book it describes a basic titration but as a result it doesn't make much sense!

    Soluble:

    Basically just a precipitation reaction, where you mix two solutions together to form a precipitate of the desired salt. To obtain the salt, you filter, wash and then dry it. They tend to use the context of Water treatment with this one! So, obtaining calcium ions from water (which makes water hard) and using a carbonate to precipitate solid calcium carbonate ions that can be filtered away from the water supply.
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    (Original post by sa97)
    Thanks alot! Please correct me if I'm wrong but for electrolysis of brine, the half equations are:

    At negative electrode:
    2H+ + 2e- --> H2

    At positive electrode
    2Cl- --> Cl2 + 2e-

    The remaining OH- and Na+ ions which do not form at any electrode bond to form NaOH.
    Perfect! So the hydroxide doesn't form at the electrode because it doesn't fit through the porous membrane, and the Sodium doesn't form at the cathode as it is higher up in the reactivity series than hydrogen (If you can understand that concept then you're well on your way to A level!).

    Edit: one other point that could be worth remembering is that if the sodium and hydroxide is still in solution they don't officially bond together as such, in solution they just remain as ions
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    They're really not gonna ask a question on nano particles as the six mark question. Theres hardly enough detail in the text book for 5 solid separate points. It will come up in the paper almost certainly, but i doubt as the six marker.
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    (Original post by sammann123)
    Perfect! So the hydroxide doesn't form at the electrode because it doesn't fit through the porous membrane, and the Sodium doesn't form at the cathode as it is higher up in the reactivity series than hydrogen (If you can understand that concept then you're well on your way to A level!).

    Edit: one other point that could be worth remembering is that if the sodium and hydroxide is still in solution they don't officially bond together as such, in solution they just remain as ions
    Do you think we would need to be aware of membrane and diaphragm used during the electrolysis of brine ?
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    Does anyone know how to make salts from insoluble bases? And I mean the experiment....
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    (Original post by sammann123)
    They're really not gonna ask a question on nano particles as the six mark question. Theres hardly enough detail in the text book for 5 solid separate points. It will come up in the paper almost certainly, but i doubt as the six marker.
    I think you're mistaken, there is plenty of points you can discuss about nano-particles and it may-be likely to pop up as the QWC.

    An example question could be like: Discuss The advantages of nanoparticles:

    • They have huge surface area to volume ratio so they are suitable to make industrial catalysts.
    • You can use nano-particles as sensors to detect specific things such as a certain type of molecule
    • Nano-tubes can be used to create lighter and stronger building materials
    • New cosmetics such as sun creams/deodorants have been made using nano particles, they do their job but don't leave any white marks
    • Nano-medicine, the idea that tine fullerenes are absorbed better by the body than most particles, this means that they can deliver drugs to specific cells of the body (where they're needed)
    • New lubricant coatings made from fullerenes which reduce friction like ball bearings and could be used in all sorts of places from artificial joints and gears
    • Nano-tubes conduct electricity, so they can be used in very tiny electric circuits for computer chips
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    Maybe I have been unintentionally biased towards myself but I got 54/60 first time round on the June 2012 paper, I find C2 relatively easy compared to C3 just learning alot of content rather than challenging stuff like titration
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    (Original post by cmorga1)
    Maybe I have been unintentionally biased towards myself but I got 54/60 first time round on the June 2012 paper, I find C2 relatively easy compared to C3 just learning alot of content rather than challenging stuff like titration
    What do you find challenging about titrations?


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    It's managable just alot harder than say percentage yields from C2!
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    (Original post by cmorga1)
    It's managable just alot harder than say percentage yields from C2!
    As in the calculations?


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    Can someone answer this please!!!

    The salt called potassium chloride is made when potassium hydroxide solution reacts
    with hydrochloric acid.


    potassium hydroxide + hydrochloric acid = potassium chloride + water

    Describe a method for making crystals of potassium chloride from potassium hydroxide solution and hydrochloric acid.


    In this method you should:
     describe how you will add the correct amount of the hydrochloric acid to neutralise the potassium hydroxide solution


     describe how you will get crystals of potassium chloride.
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    (Original post by BuddingAchiever)
    Does anyone know how to make salts from insoluble bases? And I mean the experiment....
    Step 1: add insoluble base to acid. Warm gently on a tripod and gauze (do not boil).
    Step 2: the solution changes colour as reaction occurs, showing the products forms. Excess products can be seen.
    Step 3: when the reaction is complete, filter the solution to remove excess products.
    Step 4: evaporate the water so that the salts start to form. Stop heating when you see the first salts appear at the edge of the solution. Then leave the rest of the water to evaporate slowly.
    I hope this is what you were looking for!
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    Does anyone know where to find the Jan 13 C2 paper?!
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    (Original post by Bballerjl)
    Step 1: add insoluble base to acid. Warm gently on a tripod and gauze (do not boil).
    Step 2: the solution changes colour as reaction occurs, showing the products forms. Excess products can be seen.
    Step 3: when the reaction is complete, filter the solution to remove excess products.
    Step 4: evaporate the water so that the salts start to form. Stop heating when you see the first salts appear at the edge of the solution. Then leave the rest of the water to evaporate slowly.
    I hope this is what you were looking for!

    Thank yOu very much !
 
 
 
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