CHEMISTRY 31

Fall, 2012 - Dixon

Homework Set 1 (for Exam 1)

 

Note:  Text problems will not be collected but there will be a 10 point quiz on the homework completion date unless otherwise specified

 

Chapter                                       Problems                                             Date to finish    

Set 1.1                                                                                                          Sept. 5

Ch. 1                                              1a, 5, 11, 13, 15, 20, 24,

                                                      32, 35, 37, 42, 46

                    

Turn in corrected diagnostic quiz by Sept. 5 (10 points). 

Additional Problem 1.1.

In certain areas in the world, arsenic is naturally present in ground water used for drinking at high concentrations.  This is a problem in parts of the Southwestern US where concentrations can reach 100 ppb and a much bigger problem in Bangladesh where arsenic concentrations can reach 1000 ppb.  While these levels may not cause acute problems, they lead to serious chronic health problems.  Developed countries have arsenic standards around 10 ppb (meaning water should have levels lower than that).  In selecting a method for analysis of water samples for arsenic, it is important to match method performance measures (e.g. cost of analysis) with the problem the method is investigating.  For this problem, select four performance measures (you can choose these) and discuss their importance in analyzing arsenic in water in Bangladesh and in the US.

Additional Problem 1.1 Solution

 

Set 1.2                                                                                                          Sept. 19 [NOTE CHANGE TO DUE DATE]

Ch. 3                                              1, 2, 5a-d, 11, 14, 16a-f

Ch. 4                                              4, 9, 11, 20, 21

 

Additional Problem 1.2

The cadmium concentration in a piece of cheap jewelry is analyzed by atomic absorption spectroscopy.  281.4+0.4 mg of jewelry is weighed out and transferred to a 10 mL vial to dissolve in nitric acid.  This solution is quantitatively transferred to a 100.0+0.1 mL volumetric flask and diluted to the mark.  A blank solution is prepared in a similar manner except without any jewelry.  The solution made from the jewelry is found to contain 3.94+0.07 mg/L Cd, while the blank is found to contain 0.21+0.05 mg/L Cd.  Assuming all of the uncertainties are independent, determine the concentration and uncertainty in concentration of Cd in the jewelry in parts per thousand by mass.  (5 pts)

Additional Problem 1.2 Solution

 

Set 1.3                                                                                                          Sept. 26 (no quiz)

Ch. 4                                              30

Ch. 6                                              4, 6, 8, 15-17, 19, 21, 23, 24 - also post-poned) 33, 36 postponed to HW Set 2

No Additional Problem