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    Hey
    Tricky Question
    Are Haloalkanes[halgenoalkanes] soluble or not ?? Explain ur answer.
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    (Original post by FidoDiDo)
    Hey
    Tricky Question
    Are Haloalkanes[halgenoalkanes] soluble or not ?? Explain ur answer.
    They are polar so I say that short-chain ones are.
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    (Original post by Whywhywhy)
    They are polar so I say that short-chain ones are.
    Can anyone shed any light on this? I say that the trend follows that of alcohols (i.e., short-chain ones are soluble since the functional group is polar and the rest of the chain is small).
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    (Original post by misty)
    ANyone doing 3b edexcel chem exam on thursday???
    if so, how r u revising, its a retake and when i took it the 1st time round we werent evn told we had it! heh
    I use the syllabus and this philip allan book i have for that exam its ok. just know all the tests for ions and stuff and equations u learnt throughout the AS year. Also know all the calculation stuff coz that will definately come up.
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    (Original post by meawinner)
    I use the syllabus and this philip allan book i have for that exam its ok. just know all the tests for ions and stuff and equations u learnt throughout the AS year. Also know all the calculation stuff coz that will definately come up.
    hey- what do u mean the calculation stuff? do you mean like titrations, enthalpy calculations etc..?
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    when ionic stuff dissolve with water
    does each ion form IONIC BONDS with water molecules?
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    (Original post by FidoDiDo)
    Hey
    Tricky Question
    Are Haloalkanes[halgenoalkanes] soluble or not ?? Explain ur answer.
    Take a simple example, chloromethane - CH3Cl. The clorine is more electronegative than the carbon, so the electron shared pair will spend more time at the chlorine atom, giving that bond ionic charachteristics. This is not cancelled out because there is only one C-Cl bond, so the molecule has a dipole - the chlorine end is slightly negative and the end opposite the chlorine is slightly positive. This means that water, which is also polar, may be able to split it into Cl- and CH3+, but I'm not sure if this is the case - I think a molecuce needs to be beyond a critical amount of polarity before water can disolve them.
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    (Original post by Whywhywhy)
    They are polar so I say that short-chain ones are.

    Well that would be wrong
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    (Original post by mik1a)
    Take a simple example, chloromethane - CH3Cl. The clorine is more electronegative than the carbon, so the electron shared pair will spend more time at the chlorine atom, giving that bond ionic charachteristics. This is not cancelled out because there is only one C-Cl bond, so the molecule has a dipole - the chlorine end is slightly negative and the end opposite the chlorine is slightly positive. This means that water, which is also polar, may be able to split it into Cl- and CH3+, but I'm not sure if this is the case - I think a molecuce needs to be beyond a critical amount of polarity before water can disolve them.
    Is that what I said?
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    (Original post by etomac)
    when ionic stuff dissolve with water
    does each ion form IONIC BONDS with water molecules?
    The ions are hydrated - surrounded by the polar water molecules, the direction depends on the charge of the ion. I think it'll be an ionic bond but I'm not sure to be honest, I never thought of it like that.
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    (Original post by etomac)
    when ionic stuff dissolve with water
    does each ion form IONIC BONDS with water molecules?
    Well the ions form Ion-dipole interactions with the H2O molecules..I thinks its H-bonds which is formed ..becuz u know for H-bonds .. hydrogen gets attracted to the lone pairs on another Atom.
    As u know for H-bond to form
    1- H must be attached to highly electronegative atom[Oxygen here]
    2-Lone pairs should be present.. [ Cl-,the Oxygen atom in ethanol .. etc]
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    Q: Why do ionic compounds dissolve in polar solvent?
    A: Because the polar solvent molecule break down the lattice

    Is that right?
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    (Original post by etomac)
    Q: Why do ionic compounds dissolve in polar solvent?
    A: Because the polar solvent molecule break down the lattice

    Is that right?
    Yup .. Becuz polar solvents are attracted to opposite ions in the Lattice
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    Returning for my question , the answer is

    (Original post by FidoDiDo)
    Hey
    Tricky Question
    Are Haloalkanes[halgenoalkanes] soluble or not ?? Explain ur answer.
    No .. they r immiscible becuz the C-Halogen bonds are not polar enough.
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    Hey i got this enthalpy question i want u guyz to check it up...
    a) write equation between reaction of calcium with water.

    b)When 1 g of calcium is placed in 200g of water, the temperature increases by 12.2 when the reaction is completed. The specific heat capacity of water c , is 4.2JGK
    Calculate the heat releases in the experiment.

    c)Calculate the standard enthalpy change of the reaction is KJMol for your equation in [a].

    d) use Hess' law and your results in [c] to calculate the standard enthalpy of formation of Calciumhydroxide.You also need the standard enthalpy of formation of water which is -286KJmol.

    e)calculate the volume of Hydrogen, measured at rtp, luberated in the expiremnt described in [b].
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    what should i say when the question ask

    why does HCl dissolves in water?
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    (Original post by etomac)
    what should i say when the question ask

    why does HCl dissolves in water?
    u should say becuz its a polar molecules and polar substances dissolve in polar solvents[ H2O here]
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    This is becuz .. HCL ---> H+ + Cl-
    So the partial positive sides on the water molecules[H atom] will gather around the Chloride ion[ion-dipole interactions] and separate them from other ions.
    And the partial negative sides on the water molecules[O atom] will gather around the Hydrogen ion[ion-dipole interactions] and separate them from othe ions.
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    ok thanks
    if there are 2 marks to describe why metal conduct electricity should i write
    -delocalised electrons
    -free flow of electrons under the influence of a p.d.
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    (Original post by etomac)
    ok thanks
    if there are 2 marks to describe why metal conduct electricity should i write
    -delocalised electrons
    -free flow of electrons under the influence of a p.d.
    Well i would say .. due to multiple atomic overlapping the outmost electrons get delocalised..becuz they are charged particles they act as charge carriers .. soo carry an electric charge throughout the metallic lattice ..which enables the metal to conduct electricity..
 
 
 

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