Chapter 13 Flashcards
13-1. Express the following absorbances in terms of percent transmittance:
(a) O.038
(b) 0.958
(c) 0.399
(a) %T = 10–A × 100%
= 10<sup>–0.038</sup> × 100%
= 91.6%
Proceeding in the same way, we obtain
(b) 11.0%
(c) 39.9%
13-2 Convert the following transmittance data to absorbances:
(a) 15.8%
(b) 0.492
(c) 39.4%
(a) A = – log T
= – log (15.8/100) = 0.801
Proceeding in the same way, we obtain
(b) 0.308
(c) 0.405
*13-3 Calculate the percent transmittance of solutions having half the absorbance of the solutions in Problem 13-1.
13-1 Problems
T=
(a) O.038
(b) 0.958
(c) 0.399
(a) %T = 10–0.038/2 × 100% = 95.7%
Similarly,
(b) 33.2%
(c) 63.2%
*13-4 Calculate the absorbance of solutions having twice the percent transmittance of those in Problem 13-2.
Problem 13-2
T=
(a) 15.8%
(b) 0.492
(c) 39.4%
(a) A = – log (2 × 15.8/100) = 0.500
Similarly,
(b) 0.007
(c) 0.103
13-6. A solution containing 5.24 mg/1OO mL of A (335 g/mol) has a transmittance of 55.2% in a 1.50-cm cell at 425 nm. Calculate the molar absorptivity of A at this wavelength.
*13-7 A solution containing the complex formed hetween Bi( III) and thiourea has a molar absorptivity of 9.32x103 Lmol-1cm-1 at470 nm.
(a) What is the absorbance of a 3.79 x 10-5 M solution of the complex at 470 nm in a I.00-cm cell?
(b) What is the percent transmittance of the solution described in (a)?
(c) What is the molar concentration of the complex in a solution that has the absorbance descrihed in (a) when measured at 470 nm in a 2.50-cm cell?
Define Dark Current
T d c i t s c t e i a r t i t a o r.
T d c i t s c t e i a r t i t a o r.
The dark current is the small current that exists in a radiation transducer in the absence of radiation.
Define transducer
A t i a e c t c a p o c q i a e s.
A t i a e c t c a p o c q i a e s.
A transducer is an electronic component that converts a physical or chemical quantity into an electrical signal.
Define scattered radiation (in a monochromator)
S r i r t e t e s o a m a a r o s.
S r i r t e t e s o a m a a r o s.
Scattered radiation is radiation that enters the entrance slit of a monochromator as a result of scattering.
Define source flicker noise
S f n i f n i t r s. I i u c b v i e v t c t s i (p s v, t e.)
S f n i f n i t r s. I i u c b v i e v t c t s i (p s v, t e.)
Source flicker noise is flicker noise in the radiation source. It is usually caused by variation in experimental variables that control the source intensity (power supply voltage, temperature etc.)
Define cell positioning uncertainty.
C p u i t e a w t i t p t c i e t s p f e e.
C p u i t e a w t i t p t c i e t s p f e e.
Cell positioning uncertainty is the error associated with the inability to position the cell in exactly the same position for each experiment.
Define beamsplitter
A b s i a o c t d t r i t b o o w i s t t s a t o t r.
A b s i a o c t d t r i t b o o w i s t t s a t o t r.
A beam splitter is an optical component that divides the radiation into two beams one of which is sent through the sample and the other the reference.
