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    I have a AS chemistry planning exercise to hand in for tomorrow and I haven't started it yet. I don't really have a clue on how to start any help/method/tips would be much appreciated.

    I have to come up with a practical that tests out the value for money by comparing concentrations of the acids of branded de scalers (remove scale from kettles) with different acids, some of which are organic. I also have to explain how to calculate the conc of the acids and experimental data that would be obtained.

    I need help on a method with how to work out calculations, equipment list and a safety/risk accessment.

    Basic ideas I have is that this is a titration test but from then on I'm stuck.
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    no chemists here?

    Never should have taken it for A level
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    (Original post by AnonStudent)
    no chemists here?

    Never should have taken it for A level
    ooooh sorry i didn't see that. Ok...
    First things first...always mention to put on safety specs and lab coats on at the beginning of any practical.
    Then list all the apparatus you will use.
    Wash out all the glasswear.
    Then explain how you are going to prepare your acids (whether it be dissolving powders into deionised water (250cm^3 maybe?)). You are likely to be given Mrs of these acids so you can work out roughly what the concentrations will be in a standard 250cm^3 flask.
    Then mention what concentration of base to use (eg. roughly the concentration of the acids).
    In the titration, always pipette 25cm^3 of the acid in a conical flask and add phenolphthalein (because it turns from colourless to magenta as the acid turns to base). You know the volume of the titration for the acid and the base once neutralisation has occured and you know the concentration of the base....use all this information to gather the concs of the acids.
    Always do titrations 3 times to take an average.
    In a plan, always do an example by making you're own values up....it's the best way to show how the calculations would go if you did the expt for real.
    Finally show hazcard information and things to do in an accident. Hazcards can be required from your teachers.

    If you need anything else just ask .
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    Thanks for all of that. You have helped me a lot.
    A few more questions (sorry) :
    Would Sodium hydroxide be a adequate base?
    Also I'm unsure about the de scalers being organic... is that important?
    Also it asks to apply chemical knowledge and AS work into my work but I cant think of anything relevant to titrations... only GCSE work.

    Thanks in advance.

    edit : sorry for being a bit impatient ... It's getting late and I have a lot more homework as well. I should have posted earlier. Guess I'll be staying up late no worries I don't mind waiting a bit
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    (Original post by AnonStudent)
    Thanks for all of that. You have helped me a lot.
    A few more questions (sorry) :
    Would Sodium hydroxide be a adequate base?
    Also I'm unsure about the de scalers being organic... is that important?
    Also it asks to apply chemical knowledge and AS work into my work but I cant think of anything relevant to titrations... only GCSE work.

    Thanks in advance.
    NaOH is fine (make sure you know whether the acids are monoprotic or diprotic too (have 1 hydrogen atom per molecule or 2 respectively)).
    Yes, I am unsure about them being necessarily organic too, let me check on that. Well i guess it's little techniques used in AS that aren't used in GCSE, such as, ¾ of the way through a titration you are supposed to wash the conical flask and the tip of the burette with deionised water because the friction on the tip is said to create a lot of static so not all the base from the burette reach the solution in the conical because little bits get attracted to the sides of the tip if the burette and the sides of the conical. I say this because in gcse titrations you have to get your readings withing 0.5cm^3 of eachother, in A-level it's only 0.1.
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    (Original post by AnonStudent)
    Also I'm unsure about the de scalers being organic... is that important?
    Organic acids are in general weak acids, don't know how that would help, you would need a different indicater for the weak acid/strong base titration curve etc
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    (Original post by king of swords)
    ooooh sorry i didn't see that. Ok...
    First things first...always mention to put on safety specs and lab coats on at the beginning of any practical.
    Then list all the apparatus you will use.
    Wash out all the glasswear.
    Then explain how you are going to prepare your acids (whether it be dissolving powders into deionised water (250cm^3 maybe?)). You are likely to be given Mrs of these acids so you can work out roughly what the concentrations will be in a standard 250cm^3 flask.
    Then mention what concentration of base to use (eg. roughly the concentration of the acids).
    In the titration, always pipette 25cm^3 of the acid in a conical flask and add phenolphthalein (because it turns from colourless to magenta as the acid turns to base). You know the volume of the titration for the acid and the base once neutralisation has occured and you know the concentration of the base....use all this information to gather the concs of the acids.
    Always do titrations 3 times to take an average.
    In a plan, always do an example by making you're own values up....it's the best way to show how the calculations would go if you did the expt for real.
    Finally show hazcard information and things to do in an accident. Hazcards can be required from your teachers.

    If you need anything else just ask .
    man, thanx for that. i need help with the plannig as well.
 
 
 
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