Examples, manometer Chapter

Repeat the first example in Chapter 5 where the cylinder body is charged with 100 ml of acetone and mercury is the operating fluid in the U-tube manometer (differential height is 14 in.). Discuss the potential sources of error in this measurement and how to minimize them. 

H. Example Calibration of a Trap and Measurement of a Gas Sample. In contrast to the previous example, the objective here is to measure the amount of an entire gas sample, such as the BF3 recovered in the trap-to-trap distillation discussed in Section 5.3.E. in this type of measurement a manometer is included in the calibrated volume, and it is necessary to account for the change of volume as the mercury level changes with changes in pressure. As described in Chapter 7 a constant-volume gas buret can be used, but this is somewhat cumbersome. So the simpler procedure described here is more frequently used. 

If the sucrose solution in the aforementioned membrane sac were replaced with a sodium chloride solution of the same molarity, the solution in the manometer would reach equilibrium at a point almost twice as high as that observed with sucrose because sodium chloride dissociates into two ions per molecule. If ion activity is unrestricted, the sodium chloride solution would have twice as many osmoticaUy active particles (osmoles) for the same molecular concentration as the sucrose solution. In reality, the number of active particles is less than this (0.93 for NaCl), as explained later in this chapter. The total number of individual (solute) particles present in a solution per given mass of solvent, regardless of their molecular nature (i.e., nonelectrolyte, ion, or coUoid), determines the total osmotic pressure of the solution. In blood plasma, for example, nonelectrolytes such as glucose and urea and even proteins contribute to the osmotic pressure of this body fluid. 

Chapter 11. The book by Weber [Ref. 11] is also an excellent reference for the development and physical interpretation of second-order systems (Chapter 10). It contains examples of inherently second-order systems which the reader will find quite useful. In the books by Coughanowr and Koppell [Ref. 12] and Douglas [Ref. 5] the reader can find discussions of the response of second-order systems to impulse and sinusoidal inputs. For more information on externally mounted level measuring systems, manometers, and their dynamic second-order characteristics, the reader can consult Refs. 14 (Chapter 18), 11 (Chapter 10), or the book by Shinskey [Ref. 13, Chapter 3]. 

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