CHEMISTRY 31

Spring, 2015 - 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                                                                                                          Feb. 4

Ch. 1                                              1a, 5, 11, 15, 20, 24, 32, 35, 37, 42

Text Solutions

                                                                                                                    

Turn in corrected diagnostic quiz by Feb. 4 (10 points). 

Additional Problem 1.1 (5 pts total).  A 100.0 mL sample of spring water was treated to convert any iron present to Fe2+.  Titration of this water with acidic 0.000257 M K2Cr2O7 resulted in an endpoint of 37.18 mL.  Given the reaction:  6Fe2+ + Cr2O72- + 14H+ → 6Fe3+ + 2Cr3+ + 7H2O, calculate the total concentration of iron in the sample in parts per million. Assume the density of the water is 1.000 g/mL.  (5 pts)

 

Set 1.2                                                                                                          Feb. 18

Ch. 1                                              46

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

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

                                                     

Additional Problem 1.2 (5 pts total)

The cadmium concentration in a piece of cheap jewelry is analyzed by atomic absorption spectroscopy.  281+2 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)

 

Set 1.3                                                                                                          Feb. 25 (no quiz)

Ch. 4                                              30

Ch. 6                                              4, 6, 8, 15-17, 19, 21, 23, 25

No Additional Problem