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    Could anyone give me a quick rundown on nanotechnology?
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    (Original post by Clintbarton)
    Anyone else absolutely crapping it??
    Me, definetely.
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    (Original post by TheClassicsGeek)
    Was there an empirical formula question last year? I don't think it will be a 6 mark but it's usually 4 marks which is a shame because I really detest it
    I found the empirical formula easy if you inderstand the basic steps. First find the mass of the atoms present and their Ar. Then divide the mass by the Ar for each. Then divide each answer through by the smallest. This gives the whole number ratio which equals the empirical formula. I know this sounds confusing but I hope it helps a bit.
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    (Original post by Nai18)
    Water is purified by filtering it to remove solid particles then chlorine is added to kill microbes. Silver nanoparticles can also be added to kill microbes. Fluoride is added too to help prevent tooth decay. You need to know some advantages and disadvantages of chlorination and fluoridation.
    Temporary hard water is softened by boiling it because the calcium hydrogencarbonate decomposes to form calcium carbonate (scale), removing the calcium ions from the water. Permanent hard water can be softened by adding sodium carbonate (washing soda) or passing it through an ion exchange column containing ion exchange resin with sodium or hydrogen ions in it, so when the water flows through the calcium or magnesium ions are replaced by the sodium or hydrogen ions so it is softened. Hope that helps!
    What are the advantages and disadvantages of chlorination and fluoridation?[/QUOTE]

    Chlorination
    Advantages: Kills microbes so prevents disease
    Disadvantages: Can be toxic/poisonous, can react with organic materials to form toxic products such as THM which has been linked to cancer, and no cosumer choice
    Fluoridation
    Advantages: Helps prevent tooth decay
    Disadvantages: Too much can cause fluorosis in children (the mottling of teeth), and no consumer choice)
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    (Original post by dylan65)
    Could anyone give me a quick rundown on nanotechnology?
    They are ultra small particles. This means that they have a bigger surface area and react quicker. They can be dangerous and explode easily. Can be used in windows to clean them, etc. this is basically all you need to know
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    [QUOTE=annalg;55769815]
    (Original post by Studentz001)
    Good luck to you too!
    I am very scared that the exam will have questions on hard and soft water. I think I know the basics, but not much on how hard water is softened and purified. Could you please help me?![/QUOTE


    Water is purified by filtering it to remove solid particles then chlorine is added to kill microbes. Silver nanoparticles can also be added to kill microbes. Fluoride is added too to help prevent tooth decay. You need to know some advantages and disadvantages of chlorination and fluoridation.
    Temporary hard water is softened by boiling it because the calcium hydrogencarbonate decomposes to form calcium carbonate (scale), removing the calcium ions from the water. Permanent hard water can be softened by adding sodium carbonate (washing soda) or passing it through an ion exchange column containing ion exchange resin with sodium or hydrogen ions in it, so when the water flows through the calcium or magnesium ions are replaced by the sodium or hydrogen ions so it is softened. Hope that helps!
    That definetely helped. Thanks so much for clearing that up
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    Anyone understand working out moles. I just cant remember the formula and its really stressing me out. If one comes up i going to be screwwed
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    (Original post by Gobygaga)
    They are ultra small particles. This means that they have a bigger surface area and react quicker. They can be dangerous and explode easily. Can be used in windows to clean them, etc. this is basically all you need to know
    Thanks
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    (Original post by dylan65)
    Could anyone give me a quick rundown on nanotechnology?
    They may ask you about anything to do with
    nanotechnology. But I'll tell you what I know;


    - Nanoparticles are 1-100nm across.
    - Fullerenes can be joined together to produce "nanotubes."
    - They have strong covalent bonds making them strong strong as a material such as for use in tennis rackets.

    Uses:

    • They have a large surface area to volume ratio, making them useful for industrial catalysts

    • Nanotubes are strong but light so they could be used for stronger and lighter building materials

    • Nanoparticles can be used as sensors which are extremely sensitive and we could use them to detect only one type of molecule in a solution.

    • Drug Delivery systems and nano medicine as fullerenes (hexagonal rings of carbon) are absorbed by the blood more easily.

    • Cosmetics, such as sun tan cream and deodorant.

    • In electrical circuits because Nanotubes conduct electricity.

    Not really a "quick rundown" but I hope this helps!
    Tom
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    (Original post by stressthistest)
    Anyone understand working out moles. I just cant remember the formula and its really stressing me out. If one comes up i going to be screwwed
    Just remember mass present= moles x Ar. If you remember this u can figure out the other things by making a triangle.
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    Can someone tell me how much detail we need for ionic bonding
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    (Original post by dylan65)
    Could anyone give me a quick rundown on nanotechnology?
    they include fullerenes which are hollow balls of carbon atoms arranged in hexagonal rings.

    nanotubes are tubes of fullerenes. these are used to reinforce graphite in tennis rackets because there are many covalent bonds so are very strong

    nanoscience uses: lubricants- they act like ball bearings and reduce friction
    cosmetics- work the same but no white marks
    medicine- they are small so easily absorbed by the body
    sensors- can detect very specific molecules , used in testing water
    industrial catalysts- high surface area to volume ratio

    hope this helped its basically everything you need to know
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    Remembering all those colours in b3 is very hard. The periodic table is what im guessing the 6 marker will be.
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    (Original post by barbaras99)
    Can someone tell me how much detail we need for ionic bonding
    one atom will lose electrons (so say how many etc, which depends on the group), which leaves a positively charged ion

    the other atom will gain the electrons lost from the other leaving a negatively charged ion.

    because opposite charges attract the ions are strongly attracted to each other, this is an ionic bond
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    [QUOTE=Studentz001;55770539]
    (Original post by annalg)

    That definetely helped. Thanks so much for clearing that up
    It's ok! Good luck!
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    (Original post by barbaras99)
    Can someone tell me how much detail we need for ionic bonding
    Ionic compounds and they're properties just about always come up. NaCl being a common example! I recommend learning the properties on them or I can give you a hand on that

    Atoms on the LEFT hand side of the periodic table have just one or two electrons in their outer shells and so they want to get rid of that electron .

    Atoms on the RIGHT hand side of the periodic table have electronic structures that are almost full so they want to gain an electron or two to have a full outer shel!

    Once you know that, you can apply it to any example they give you tomorrow.
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    (Original post by Nomes24)
    Just remember mass present= moles x Ar. If you remember this u can figure out the other things by making a triangle.
    thanks so much
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    (Original post by SmashedIt)
    can anyone help answer this, what properties make ethanol a useful solvent?
    i think its because it can mix oils and water eg in perfumes
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    (Original post by Positivedani)
    Ooh is that the salts chapter? I can explain it kind of (also provides some revision for me)
    if you mix a metal+acid you get a salt+hydrogen
    if you mix a metal oxide/hydroxide you get a salt+water (since there is an extra oxygen molecule frim the oxide or hydroxide)
    and an acid with a carbonate gives a salt and carbon dioxide and water!
    then there is making salts:
    you will be told in the question whether the salt is soluble or insoluble etc and the eqiptment will also be a clue as to which method to use!
    making insoluble salts: precipitation. Add your two solutions together and then one will precipitate. Filter this and wash with water to get your salt.
    making soluble salts: 2 soluble bases. This is a titration where you add an indicator eg universal indicator to your acid and then you add a certain volume of alkali until you can see that it is neutralised signalised by a colour change. Repeat this experiment using no alkali but the same measurements. Then you use heat to evaporatate amd crystallise your salts.
    making soluble salts: one soluble and an insolube base. Eg copper oxide and sulfuric acid. Add the powdered copper oxide in excess to the acid(warm for a fast rate of reaction). Add it in excess so you know it has all reacted. Then you filter, evaporate and crystallise!
    fINALLY
    salt equations. Eg copper oxide+hydrochloric acid = copper CHLORIDe and water(it is a metal oxide)
    eg. Magnesium hydroxide+sulfuric acid= magnesium SULFATE and water. Basically you take th first letter of the metal hydroxide and add it to the first letter of the acid!
    hope that helped x
    Just remember
    MASH
    BAWS
    CAWCS
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    anyone got any ideas what some of the c3 questions will be on?? Also, help on titration calculations??
 
 
 
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