Question

 

A. Design a buffer that has a pH of 10.20 using one of the weak base/conjugate acid systems shown below.

Weak Base	Kb	Conjugate Acid	Ka	pKa
CH3NH2	4.2×10-4	CH3NH3+	2.4×10-11	10.62
C6H15O3N	5.9×10-7	C6H15O3NH+	1.7×10-8	7.77
C5H5N	1.5×10-9	C5H5NH+	6.7×10-6	5.17

How many grams of the chloride salt of the conjugate acid must be combined with how many grams of the weak base, to produce 1.00 L of a buffer that is 1.00 M in the weak base?

grams chloride salt of conjugate acid = _____

grams weak base = _______

B. A 30.6 mL sample of a 0.581 M aqueous hypochlorous acid solution is titrated with a 0.205 M aqueous barium hydroxide solution. What is the pH after 28.9 mL of base have been added? pH =______

C. A 23.8 mL sample of 0.240 M diethylamine, (C₂H₅)₂NH, is titrated with 0.256 M nitric acid.
After adding 9.91 mL of nitric acid, the pH is . ______
(Use the Tables link in the References for any equilibrium constants that are required.)

D. When 12.0 mL of a 7.14×10^-4 M lead acetate solution is combined with 15.0 mL of a 3.88×10^-4 M sodium bromide solution does a precipitate form? _____ (yes or no)

For these conditions the Reaction Quotient, Q, is equal to _____.

E.

The K_sp for SrSO₄ is 3.4×10^-7. What is the molar solubility of SrSO₄ in 0.046 M Sr(NO₃)₂?

A.5.8×10^-4M

B.2.7×10^-5M

C.7.4×10^-6M

D.1.6×10^-8M

E.1.6×10^-4M

Answer 1