CHEM100B_Homework Solutions_Skoog PIA6 IM 01-34

CHEM100B_Homework Solutions_Skoog PIA6 IM 01-34 -...

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Skoog/Holler/Crouch Chapter 1 Principles of Instrumental Analysis, 6 th ed. Instructor’s Manual 1 CHAPTER 1 1-1. A transducer is a device that converts chemical or physical information into an electrical signal or the reverse. The most common input transducers convert chemical or physical information into a current, voltage, or charge, and the most common output transducers convert electrical signals into some numerical form. 1-2. The information processor in a visual color measuring system is the human brain. 1-3. The detector in a spectrograph is a photographic film or plate. 1-4. Smoke detectors are of two types: photodetectors and ionization detectors. The photodetectors consist of a light source, such as a light-emitting diode (LED) and a photodiode to produce a current proportional to the intensity of light from the LED. When smoke enters the space between the LED and the photodiode, the photocurrent decreases, which sets off an alarm. In this case the photodiode is the transducer. In ionization detectors, which are the typical battery-powered detectors found in homes, a small radioactive source (usually Americium) ionizes the air between a pair of electrodes. When smoke enters the space between the electrodes, the conductivity of the ionized air changes, which causes the alarm to sound. The transducer in this type of smoke detector is the pair of electrodes and the air between them. 1-5. A data domain is one of the modes in which data may be encoded. Examples of data domain classes are the analog, digital and time domains. Examples of data domains are voltage, current, charge, frequency, period, number.
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Principles of Instrumental Analysis, 6 th ed. Chapter 1 2 1-6. Analog signals include voltage, current, charge, and power. The information is encoded in the amplitude of the signal. 1-7. Output Transducer Use LCD display Alphanumeric information Computer monitor Alphanumeric information, text, graphics Laser printer Alphanumeric and graphical information Motor Rotates to change position of attached elements 1-8. A figure of merit is a number that provides quantitative information about some performance criterion for an instrument or method. 1-9. Let c s = molar concentration of Cu 2+ in standard = 0.0287 M c x = unknown Cu 2+ concentration V s = volume of standard = 0.500 mL V x = volume of unknown = 25.0 mL S 1 = signal for unknown = 23.6 S 2 = signal for unknown plus standard = 37.9 Assuming the signal is proportional to c x and c s , we can write S 1 = Kc x or K = S 1 / c x After adding the standard 2 x xs s Vc SK VV ⎛⎞ + = ⎜⎟ + ⎝⎠ Substituting for K and rearranging gives, 1 21 () ss x x sx SVc c SV V SV = +−
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Principles of Instrumental Analysis, 6 th ed. Chapter 1 3 c x 4 23.6 0.500 mL 0.0287 M = 9.00 10 M 37.9(0.500 mL + 25.0 mL) (23.6 25.0 mL) ×× −× 1-10. The results are shown in the spreadsheet below.
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This note was uploaded on 05/26/2010 for the course CHEM CHEM 100B taught by Professor Pomeroy during the Winter '10 term at UCSD.

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CHEM100B_Homework Solutions_Skoog PIA6 IM 01-34 -...

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