Question

The electronic absorption spectrum UI (Cr(NH3)6]3+ (aq) is shown in Figure 11.5. One of the observed peaks is centered at about 303 nm. 1.a. What is the approximate value of the wavelength for the two other peaks? Which one of these three peaks falls in the visible region of the electromagnetic spectrum? The wavelength at this peak is (Amax), and this transition accounts for the color of the complex ion in solution. The energy of the transition occurring at Amax equals the energy difference between t" and e* molecular orbitals in this complex (40) (Figure 11.1). Calculate this energy in J. What color is a solution containing this complex ion? (see Table 11.1) How many d-electrons are in the Cr3+ ion? Add to this the number of electrons contributed by ligands (six ligands contribute 2 electrons each). Using Figure 11.1, determine the electronic configuration of (Cr(NH3)6]3+ Electronic Absorption Spectrum 0.200 0.150 Absorbance 0.050 0.000 200 250 300 350 400 450 500 550 600 Figure 11.5 Electronic absorption spectrum of [Cr(NH3)6]3+(aq)
   

Answer 1

In case of cor (43) ] 3+ ron, one of the observed peaks is centred at about 303 am 27 @ Approximate value of the ecuavelength of two other peake 2 353 nm and 465 nun

396 Range of wavelength for wisible radiation 9 (400-900)mm u. The peak at around 465 am falls in the visible region of Electromagnelse spectrum . The wavelength at this peak is Aman . X max = 465 nm 1. ① Energy difference can also be expressed as the play LAE a he may SE + energy difference between th and et molecular orbitals, which is nothing but to .. (0E = 60] 7 mar Now, ha 6.626 x 1024 IS a 3x108 m/s may a 465 nm 465x109 m. as do 6.626 X10-34% 3x108 4 465 x 10 9 02 0.0427 x 10 6 34+8+1) do = 0,0427x10-17 0.7 4.27 x 10-19 J

ea of the complex is 1.7 @ As seen from the spectra, the complex absores at 465 cm (max) . The colour of light absorbed by the complex Blue-green colour. As per complementary colour Meule, the colour emitted by the complex is complemente do this colour absorbed by the complexe. The colour anitted by the comply u actually the colour that we observe. 1. As por complementary colour sule, The colour emitted by the complex is soddish yellow :Colour of the solukion containing this compleston is medelishayellow. 1% © 2x3t has 3 d electrons. e. It us a of system. There are 6 ligands (NH3). Each digand contribute a decrons. . Total no. of electrons contributed by ligands. 2x6 212. c. Total no. of elections in the complex (3+12) - 15 . by 3t is a d system. Electronic Configuration of Cu a [Ar] 3d54e2 Electronic Configuration of oxºt = ] 3