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    Why on earth is the answer to this 'A'?

    I thought that the end point was always pink when using phenolphthalein
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    (Original post by upthegunners)
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    Why on earth is the answer to this 'A'?

    I thought that the end point was always pink when using phenolphthalein
    You are adding acid to base.

    The indicator in base is red and the end point is considered when the equivalence point is reached between pH8-10, which is when the phenolphthalein turns colourless.
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    (Original post by charco)
    You are adding acid to base.

    The indicator in base is red and the end point is considered when the equivalence point is reached between pH8-10, which is when the phenolphthalien turns colourless.
    but is this not a neutralization reaction therefore meaning that the end point is neutral? How am I meant to know it's A?
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    (Original post by charco)
    You are adding acid to base.

    The indicator in base is red and the end point is considered when the equivalence point is reached between pH8-10, which is when the phenolphthalein turns colourless.
    Sorry to bother you again Charco, but why is CH3COCH3(l) a better solvent for cyclohexanol than CH3CH2CH2CH2CH2CH3 (l)?

    Thank you very much for your help.
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    (Original post by upthegunners)
    but is this not a neutralization reaction therefore meaning that the end point is neutral? How am I meant to know it's A?
    The actual end point of this titration (equivalence point) is at pH 7, but 1 more drop then turns the mixture to pH10 so you see the red colour turn colourless.
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    (Original post by charco)
    The actual end point of this titration (equivalence point) is at pH 7, but 1 more drop then turns the mixture to pH10 so you see the red colour turn colourless.
    Are they not asking for the end point? In my text book it clearly says that it would be pink..

    I am not saying you're wrong I am just really unsure why this is...seems really odd..

    Endpoint=neutral

    Colour of neutral solution in phenolphthalein= pink

    so why is it not 'B'? :lol:
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    (Original post by upthegunners)
    but is this not a neutralization reaction therefore meaning that the end point is neutral? How am I meant to know it's A?
    The term "end point" is when you've neutralised the solution being tested.

    And you should know the colour changes of the indicators in your syllabus.
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    (Original post by upthegunners)
    Sorry to bother you again Charco, but why is CH3COCH3(l) a better solvent for cyclohexanol than CH3CH2CH2CH2CH2CH3 (l)?

    Thank you very much for your help.
    The efficiency of solvents is a balance between the solvent intermolecular forces acting (solvent-solvent), the solute intermolecular forces (solute-solute) and the solvation forces (solvent - solute).

    All particles exhibit van der Waals induced dipole attractions, the strength of which is dependent on the available surface area, which is turn is a function of the relative mass and shape.

    The hydrocarbon is relatively large and has appreciable induced dipole attractions with itself.

    The ketone has also permanent dipole -dipole interactions with itself, but relatively weak solvation forces.

    However, cyclohexanol can interact with itself via both induced dipole, permanent dipole and hydrogen bonding.

    The hydrocarbon cannot disrupt these forces using only induced dipole, but the ketone can interact via dipole -dipole with the cyclohexanol and also it can form hydrogen bonds between the lone pairs on the oxygen and the hydrogen of the cyclohexanol. This extra bonding tips the balance in favour of propanone as a solvent.
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    (Original post by TheGrinningSkull)
    The term "end point" is when you've neutralised the solution being tested.

    And you should know the colour changes of the indicators in your syllabus.
    It quite clearly states that the end point colour of phenolphtalein is pink and not colourless in my edexcel textbook

    however; the answer in this question, for some absurd reason, is A.
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    (Original post by charco)
    The actual end point of this titration (equivalence point) is at pH 7, but 1 more drop then turns the mixture to pH10 so you see the red colour turn colourless.
    Doesn't it go from pink to colourless?
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    (Original post by charco)
    The efficiency of solvents is a balance between the solvent intermolecular forces acting (solvent-solvent), the solute intermolecular forces (solute-solute) and the solvation forces (solvent - solute).

    All particles exhibit van der Waals induced dipole attractions, the strength of which is dependent on the available surface area, which is turn is a function of the relative mass and shape.

    The hydrocarbon is relatively large and has appreciable induced dipole attractions with itself.

    The ketone has also permanent dipole -dipole interactions with itself, but relatively weak solvation forces.

    However, cyclohexanol can interact with itself via both induced dipole, permanent dipole and hydrogen bonding.

    The hydrocarbon cannot disrupt these forces using only induced dipole, but the ketone can interact via dipole -dipole with the cyclohexanol and also it can form hydrogen bonds between the lone pairs on the oxygen and the hydrogen of the cyclohexanol. This extra bonding tips the balance in favour of propanone as a solvent.
    That is a fantastic explanation; however I am finding it difficult to understand due to my lack of knowledge (I am only at ASLevel)

    Is it basically because the ketone can form stronger bonds with the cyclohexanol?
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    (Original post by upthegunners)
    It quite clearly states that the end point colour of phenolphtalein is pink and not colourless in my edexcel textbook

    however; the answer in this question, for some absurd reason, is A.
    It's because you've started with a base. So you go from pink to colourless.

    Colourless in this case is the end point.
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    (Original post by TheGrinningSkull)
    It's because you've started with a base. So you go from pink to colourless.

    Colourless in this case is the end point.
    surely the end point will be the same as starting with an Acid or a base?

    The end point is when it is neutral
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    (Original post by upthegunners)
    surely the end point will be the same as starting with an Acid or a base?

    The end point is when it is neutral
    It's only 2 colours, there is no other intermediate colour, so you'd have to notice a colour change for it to be neutralised.

    Like so: http://www.youtube.com/watch?v=MhLKxDtYWFU&t=1m10s
 
 
 
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