CHEMISTRY 133

Spring, 2016 Homework Set 1

Only Problems in Bold are Submitted for Grading

Set 1.1 - Complete for quiz on Feb. 4

From Rubinson and Rubinson:  6.1, 6.2, 6.3, 6.5, 6.6, 6.7 [not collected]

Additional Problems (goes to pdf document) To be turned in (those in bold)

Homework Set 1.2

Complete for quiz on Feb. 18

R&R Problems:  17.2, 17.3, 17.4

Additional Problems (goes to pdf document)

Data Set for HW1.2.1 problem

Homework Set 1.3

Complete by Mar. 1 (but no quiz planned - Mar. 1 = Exam 1 date)

1.3.1.  Which type of noise is best reduced by shielding the critical electronics?

1.3.2.  An instrument measures the concentration of a compound in a river that varies on the order of minutes.  Most of the noise associated with the measurement occurs at frequencies greater than 1 Hz.  Suggest a method (analog or digital) to increase the signal to noise ratio.

1.3.3.  What type of noise can be reduced by using internal amplification in a transducer?

1.3.4.  What type of noise can be reduced by cooling electrical components?

R&R 6.13

5.  A sample is measured 12 times by a spectroscopic method.  The average concentration and standard deviation in the average are found to be 5.2+0.7 μM.  With the assumptions made below answer the following questions:

Assume: 1) noise is purely random, 2) the noise is defined as the standard deviation, and 3) that the standard deviation is well-represented.  (The third assumption allows you to avoid using t-factors in signal averaging)

a)  What signal to noise ratio would be expected in a single measurement?

b)  What is the signal to noise in the average value for the twelve measurements?

c)  A researcher needs to have the noise be less than 2% of the value in a particular experiment.  How many measurements should she make?

Harris Text: Ch. 13:      1, 5, 10