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Raising the temperature of a solvent

  1. Jun 16, 2003 #1
    Raising the temperature of a solvent (eg water) alters the maximum solubility why?
     
    Last edited by a moderator: Feb 5, 2013
  2. jcsd
  3. Jun 16, 2003 #2

    E8

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    Because raising the temperature 'loosens' electrostatic interactions between molecules thus making it easier for water to pry themselves in between and form a clathrate (cage) around individual molecules or ions thereaby separating them. Basically your increasing the kinetic energy of molecules and therefore their moving around the solution at a much higher rate when they are at higher temperatures.
     
  4. Jun 16, 2003 #3
    >>>thus making it easier for water to pry themselves in between <<<

    so its more to do with the temp of the thing your trying to dissolve not so much the medium E8?
     
  5. Jun 16, 2003 #4
    No, it is more about the temprature of the medium you are dissolving In.
    To understand this you must first understand how dissovling happens.
    The dissolved material has somekind of bound between its molecules (for example, in NaCl the bounds are Ionic), when a certain material gets dissolved in a certain medium, it means that the bound between the molecule of the matterial were broken (even if not all of them), and re-formed with the medium.
    For example, let's take NaCl (table salt), being dissolved in H2O (water), the molecules of H2O has a positive and negative side (due to the difference in electronegativity of H and O, and also due to the shape of H2O), in other words, the molecules of Water are being attracted to each other by a electrostatic force (the positive side of a water molecule attracts the negative side of antoher water molecule, forming hexagons if water is cold).
    Now, when you put NaCl in that water, the positive side of the water molecule will head towards the negative Cl ion, and the negative side of other water molecules will head towards the positve Na ion, and those water molecules will form a cage round the ions, therefore taking teh ions out of the NaCl block (or, actually, dissolving NaCl !).
    Now that you have an idea how this happens, let's see the effect of temprature on that.
    When you raise the temprature of water, the kinetic energy of the water molecules will become bigger (or in other words, the average speed of each molecule will become higher), so the water molecules will have more energy to beat the force between the ions of NaCl, and form the cages (and it will also be easier since the electrostatic force between the water molecules will become less effective on the movement of the waster molecules).

    (edited for a missing letter)
     
  6. Jun 16, 2003 #5
    Re: Dissolving

    i don't mean to be picky, but you mean 'how'. 'why' is for philosophy.
     
  7. Jun 17, 2003 #6
    Thankyou for your time and replies STAii and E8
     
  8. Jun 18, 2003 #7
    this is because.

    i feel,
    When you heat a object it expands.the same hapens inside the molecule of a solute. the inter molecular space expands there by letting space for more particles of solvent to deposite or to be there. I feel this is the cause. i am not good in explaining. so please forgive me for any mistakes.
     
  9. Jun 18, 2003 #8
    this is because.

    i feel,
    When you heat a object it expands.the same hapens inside the molecule of a solute. the inter molecular space expands there by letting space for more particles of solvent to deposite or to be there. I feel this is the cause. i am not good in explaining. so please forgive me for any mistakes.
     
  10. Jun 18, 2003 #9
    No problem thomo :wink:
    Well benzun_1999, it is sometimes explained the way you are saying, but you see, what really happens in reality is not that the molecules of the matterial simply slip in the molecular spaces of the medium.
     
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