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    Examples of pH Values

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    LoRdBOy
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    Examples of pH Values

    Post by LoRdBOy on Sun Sep 27, 2009 5:33 am

    Examples of pH Values


    The pH of a solution is a measure of the molar concentration of
    hydrogen ions in the solution and as such is a measure of the acidity or
    basicity of the solution. The letters pH stand for "power of hydrogen" and
    numerical value for pH is just the negative of the power of 10 of the
    molar concentration of H+ ions.



    The usual range of pH values encountered is between 0 and 14, with 0
    being the value for concentrated hydrochloric acid (1 M HCl), 7 the value
    for pure water (neutral pH), and 14 being the value for concentrated
    sodium hydroxide (1 M NaOH). It is possible to get a pH of -1 with 10 M
    HCl, but that is about a practical limit of acidity. At the other extreme,
    a 10 M solution of NaOH would have a pH of 15.

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    Numerical examples from Shipman, Wilson and Todd.
    In pure water, the molar concentration of H+ ions is
    10-7 M and the concentration of OH- ions is also
    10-7 M. Actually, when looked at in detail, it is more accurate
    to classify the concentrations as those of [H3O]+
    and [OH]-. The product of the positive and negative ion
    concentrations is 10-14 in any aqueous solution at 25°C.
    An important example of pH is that of the blood. Its nominal value of
    pH = 7.4 is regulated very accurately by the body. If the pH of the blood
    gets outside the range 7.35 to 7.45 the results can be serious and even
    fatal.





    If you measure the pH of tap water with a pH meter, you may be
    surprised at how far from a pH of 7 it is because of dissolved substances
    in the water. Distilled water is necessary to get a pH near 7.
    Meters for pH measurement can give precise numerical values, but
    approximate values can be obtained with various indicators. Red and blue
    litmus paper has been one of the common indicators. Red litmus paper turns
    blue at a basic pH of about 5, and blue litmus paper turns red at an acid
    pH of about 8. Neither changes color if the pH is nearly neutral. Litmus
    is an organic compound derived from lichens.
    Phenolpthalein is also a common indicator, being colorless in solution
    at pH below 8 and turning pink for pH above 8.



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    Future Eng.
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    Re: Examples of pH Values

    Post by Future Eng. on Mon Sep 28, 2009 8:43 pm

    Thanking you a lot sweet dear.

    this is the fundamental things of chemistry.

    all da best to all

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    Talib Al_Munawri
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    Re: Examples of pH Values

    Post by Talib Al_Munawri on Mon Dec 21, 2009 8:41 am

    all da best

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    Re: Examples of pH Values

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