Question

2. [Chang, 9.39] The rate-determining step of the bromination of acetone involves breaking a carbon-hydrogen bond. Estimate the ratio of the rate constants kc-/kc-n for the reaction at 300 K. The frequencies of vibration for these particular bonds are VC- H 3000 cm-1 and VC- D 2100 cm-1. The wavenumber (ū) is given by v/c, where v is the frequency in s and c is the speed of light in a vacuum (3.00 x 10 m.s ).

Answer 1

The frequencies of vibrations for the bonds are, Ved a 3000 cut ano VC-D ~ 2100 int. co velocity of Now 7.a .& 9 C.7 right in vacuum So WH . 2 3·00xholms & 3x208 mis x 3000 cut 2 3 4208 mis x 3000 x 200 m² gx 2013 S -0 = 3x20 mis x 2100 x 100 int & Deo = 3XL08 m.5 x 2100 6.38 Los Now for Me reduced mass, frequency of vibration, we have , , , , M M / »k. 411²222} Ko force constant the bonds, - - Me Moh Me & MD/H for bith Reo 471?c? V MED 22 Men Am Now, Mca 12 gm.mel MA I gm.meh Mo Hence. Mch/UCD & 12+1 , 14. I 12x2 226 13. Se keld & x²) x 7 ke-D (6.3 x 113) 2 x 12 ł 1.0989 2 12 +2