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Homework Help: Chemistry 12th grade please help

  1. Mar 7, 2010 #1
    1. The problem statement, all variables and given/known data
    1 - An aqueous solution of NaOH (strong base), of concentration 0.10 mol/L was gradually added to a solution of HCl (strong acid), molar concentration of 0.08 mol/L. Select the graphic that provides the concentrations of different species during this addition.

    2- AgBr (s) -> Ag+ (aq) + Br- (aq), Ks=7,7*10^-13 and Kf=10^21

    2.1 - calc the solubility of AgBr in water.
    2.2 - calc the solubility of AgBr in a solution of KCN 0,10 mol/L.

    3 - A sample of 10.0 mL of a solution of NH3 (aq) concentration 0.15 mol/dm^3, is titrated with a solution 0.10 mol/dm^3 in HCl (aq).
    3.1 - What volume of HCl worn to the point of equivalence?
    3.2 - What the pH at equivalence point?
    3.3 - What is the pH at the time of titration is added to half the volume of titrant worn to the point of equivalence.?

    4 - The following figure (figure number 2) represents the titration of a solution of phosphoric acid with a solution of sodium hydroxide.
    As phosphoric acid is an acid polyprotic the titration curve has several points of equivalence and also a number of buffer zones.
    4.1 - What are the buffer zones and the species that determine the buffer effect in each of these areas?
    4.2 - What relationship exists between the volume of titrant spent by the first equivalence point and the volume of titrant spent between the first and second equivalence point?

    2. Relevant equations

    3. The attempt at a solution
    1 - I really dont know how to do this :S
    2 - 2.1 I got 8.8*10^-7 mol/dm^3
    2.2 i think it is 8.8*10^-7 mol/dm^3, too.

    3 - I ve just write the eq.: NH3 + HCl -> NH4Cl but I dont know how o solve the problem.

    4.1 -
    4.2 - they're equal.

    Please help me...I've test tomorrow :S :S :S

    Attached Files:

  2. jcsd
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