[Rachel.F]

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?


My attempt:
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