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GC. Normality, equivalent weight, valance factors

Discussion in 'DAT Discussions' started by 299678, Mar 6, 2010.

  1. 299678


    Dec 14, 2009
    I am so confusing about Normality, equivalent weight, valence factor.
    This is what I summarized it so far, could you be able to explain those concepts?

    The normality is defined as the number of gram equivalents of solute present per liter of the solution at any given temperature.

    Normality = Molarity x i

    Normality = Molarity x # of electrons traveled.

    Equivalent weight = atomic weight /valence factor or
    = molecular weight / basicity or acidity
    So equivalent weight of oxygen is 16/2 = 8

    Valence factor – How many electrons does an element need to be saturated, charge (with no sign), for example, valence factor for Hydrogen is 1, Oxygen is -2, and Al has +3 and H2SO4 has valence factors of –
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  3. 299678


    Dec 14, 2009
    ? nobody?
  4. UCB05

    UCB05 2+ Year Member

    Jun 14, 2009
    Normality is essentially a guage of participation in a specific reaction, represented by the i term. If in a redox reaction a molecule donates 2 electrons, its normality is 2M. If the same molecule participates in a single-displacement reaction, it has a normality of 1M. If that same molecule happens to be triprotic, it might react in a titration reaction at a normality of 3M. Normality is reaction-specific. It's a shortcut to skip the step where you think "hm, it can react 3 times, so I have to remember to multiply its effective concentration by 3"

    I'm kinda shady on the equivalent weight/valence factor stuff, but if you understand normality, equivalent weight is essentially normality in grams. Since 1 mol of H+ (1g/mol) reacts with 1 mol of NaOH (40g/mol), the equivalent mass is 1g H== 40gNaOH.

    I'd be willing to say you wont need to know this for the DAT, since equivalent weight was only used because scientists didn't yet know what a "mole" of anything was, so they had to experimentally eyeball things. '40g of NaOH reacts with 36.5 grams of HCl. Hm, we'll call that their equivalent mass...' Now we know that 1mol of NaOH reacts in equivalence with 1mol HCl
  5. Maygyver

    Maygyver 5+ Year Member

    Jun 13, 2008
    Another good example of use of normality is polyprotic acids. For example, if you have H2SO4, then you have 2 mols of H+ per mol of acid that can react with a base.
  6. JBarr29

    JBarr29 5+ Year Member

    Aug 15, 2008
    I'm pretty sure thats not something that you'd really have to concern yourself with either.
  7. 299678


    Dec 14, 2009
    Thank u for all ~

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