Mock Quiz 2 Chem 104 PDF

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Mock Quiz Unit 2 Ray Christian...

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Practice Quiz 2 1.

In a solution of 150 mL of 0.9 M HI titrated by 350 mL of 0.6 M NaOH what is the pH?

2.

A solution of sulfurous acid and ascorbic acid are mixed together in water. Identify all major species. a. H2 SO3

b. c. d. e. f. g. h.

H2O  H3O+ H2C6H6O  6 HC6H6O6- 2C6H  6O6

HSO3- SO32-

3.

What is the concentration of a 3.45 M compound when it has been completely deprotonated with pKa1= 2.2, pKa2=4.3, pKa3=9.7?

4.

Which of the following will produce a buffer system when equal volumes are mixed? a. 2 M HF titrated with 1 M NaOH

5.

b.

2 M HCN titrated with 2 M NaCN

c.

2 M C6H5NH  3NO  3 titrated with 2 M NaOH

d.

2 M HBr titrated with 1 M NaOH

e.

2 M CH3NH3Cl  titrated with 2 M NaCl

Choose the best pair that buffers around 9: a. HF and NaF b.

CN and KCN

c.

RbI and NaCl

d.

HC3H5O2 and NaC3H5O2

e.

Sr(OH)2 and H2SO4

6.

Calculate the pH of a solution that is 0.75 M HF and 0.89 M KF:

7.

Calculate how many moles of NaCN are needed to create a 1 L solution at a pH of 10.76?

8.

Rank the following compounds from acidic to basic and identify the third most acidic: a. KOH b. HNO3 c. HF d. C5H5 NHBr  e. NaCH3COO f. KClO g. KCN h. NH4Cl

9. A buffer with pH=7.5 is desired. Which of the following pairs would be best for making this buffer. And which needs to be in excess to reach the desired pH? H3A (Ka1=5.5e-3,  Ka2=1.7e-7, Ka3=5.1e-12)

a.

- H3A / H2A   with H3A   in slight excess

 slight excess b. HA2- / H2A- with A3- in

c.

- 2- - H2A   / HA with H2A   in slight excess

- -   in slight excess d. H3A / H2A   with H2A

e.

- 2- 2- H2A   / HA with HA in slight excess...