problem solving

Buffers 

1.      A buffer is prepared by adding 0.60 moles of HC2H3O2 and 2.0 moles of NaC2H3O2 to enough water to make 1.0 L of solution. What is the pH? (Ka = 1.8 x 10-5)

2.      What is the pH of a solution prepared by dissolving 15.0 g of NaHCO3 and 15.0 g of Na2CO3 in enough water to make a 0.250 L solution? (Ka = 5.6 x 10-11)

3.      4.13 g of NaC9H7O4 is added to 250. mL of a 0.150 M HC9H7O4 solution. What is the pH of the buffer? Ka = 2.75 x 10-5

4.      Calculate the pH of a buffer solution that is 0.50M NH3 and 0.20M NH4Cl. pKb = 4.75

5.      Calculate the [H+] and the pH in a solution that is 0.420 M in NaX and 0.793 M in HX given that the Ka of HX is 3.53 x 10−9.  

Titration = Strong / Strong & Weak / Strong

1.      Strong Acid / Strong Base

25.0mL of a 0.100M HCl solution is titrated with 0.100M NaOH solution. 

a.      What is the pH before any base is added? 

b.      What is the pH after 10.0 mL of base is added? 

c.       What is the pH after 22.5 mL of base is added?

d.      What is the pH after 30.0 mL of base is added? 

2.      Weak Acid / Strong Base

25.0mL of a 0.100M Acetic Acid solution is titrated with 0.100M NaOH solution. 

a.      What is the pH before any base is added? 

b.      What is the pH after 10.0 mL of base is added? 

c.       What is the pH after 25.0 mL of base is added?

d.      What is the pH after 40.0 mL of base is added? 

3.      A 2.00 L solution contains 0.603 M NH3 and 0.403 M NH4A.  (The Kb of NH3 is 1.86⋅10−5).

a.       What is the pH of this solution?               

b.      What is the pH of this solution after 0.209 mol of HCl are added to the solution?           

c.       What is the pH of this solution after 0.418 mol of HCl are added to the solution?

Solubility

1.       The molar solubility of Cu3PO4 is 4.16⋅10−2M.  Calculate the Ksp for Cu3PO4.

2.       What is the molar solubility of CaF2 in a solution containing 0.200M NaF? Ksp = 1.46 * 10-10

3.       Will a precipitate form in a solution that is 0.0150M Pb(NO3)2 and 0.00150M NaBr ?