Analytical Chemistry

2001) A solution is in equilibrium with solid PbCl2. Some NaCl is added.

a) Will the concentration of Cl- in solution increase or decrease?
b) Will the concentration of Pb+2 increase or decrease?

2002) Consider a solution in equilibrium with solid CaSO4.

a) If some solid NaNO3 is added, will the solubility of CaSO4 increase, decrease, or stay the same?
b) If some solid Na2SO4 is added, will the solubility of CaSO4 increase, decrease, or stay the same?
c) If some solid CaSO4 is added, will the solubility of CaSO4 increase, decrease, or stay the same?

2003) After an excess of Ag(NO3) has been added to an aqueous solution containing K(SCN)

a) Is the charge on the surface of colloidal Ag(SCN) positive or negative?
b) What ion is the source of this charge?
Ag+, NO3-, K+, SCN-
c) Which ion predominates in the solution layer next to the particle?
Ag+, NO3-, K+, SCN-

2004) A mixture of two chemicals was spilled in the ground. When the area was later analyzed, neither chemical was found at the original site and the two chemicals had separated. Referring to the picture below, which chemical is more soluble?

A, B, neither

2005) You have 100 mL of solvent available to do an extraction. Which will give a better separation?

1 extraction with 100 mL
2 extractions with 50 mL
5 extractions with 20 mL

2006) The center titration curve shows the precipitation titration of X- with Ag+.


a) How will the titration curve change when the Ksp is larger (such as a change from
10-9 to 10-7)?

A, B, or no change
C, D, or no change

b) How will the titration curve change when the solutions are equally more concentrated?

A, B, or no change
C, D, or no change

2007) Consider a pH titration of CH3COOH in a flask with KOH from a buret. What is the primary species that controls the pH in the flask

a) at the start? CH3COOH, CH3COO-, K+, OH-, H+
b) halfway to the equivalence point? CH3COOH, CH3COO-, K+, OH-, H+
c) at equivalence? CH3COOH, CH3COO-, K+, OH-, H+
d) after equivalence? CH3COOH, CH3COO-, K+, OH-, H+

2008) When standardizing a pH meter, what pH buffer solution do you use first?

4, 7, 10

2009) You have available HCl, NaOH, CH3COOH, and CH3COOK. What possible pairs can be used to make a buffer?

HCl and NaOH
HCl and CH3COOH
HCl and CH3COOK
NaOH and CH3COOH
NaOH and CH3COOK
CH3COOH and CH3COOK

2010) Which will be the better indicator to use when titrating HOCl (Ka = 3.0x10-8) with KOH?

thymolphthalein (pKa 9.9)
bromothymol blue (pKa 7.10), or
bromocresol green (pKa 4.66)




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