Question

10 of 14 Questions Assignment Score: 1167/1400 Resources Hint Check Answer 95/100 < Question 10 of 14 > 6 Question 2 of Attempts Correct When a rotating disk electrode (RDE) is held at a high enough potential, the rate of the reaction is governed by the diffusion rate, the rate at which the analyte diffuses through the diffusion layer to the electrode. The thickness of this diffusion layer, 8, is calculated as 100/100 7 Question 1 of co Attempts Correct 8 = 1.6101/3-1/2, 1/6 98/100 8 Question 2 of co Attempts Correct where D is the diffusion coefficient (m?/s), v is the kinematic viscosity of the liquid (m?/s), and o is the rotation rate (radians/s) of the electrode. Additionally, the current density, J (A/m²), is measured using the Levich equation, 95/100 9 Question 2 of co Attempts Correct J = 0.62nFD2/30112,-1/6 Co 0/100 10 Question O of co Attempts where n is the number of electrons transferred in the half-reaction, F is the Faraday constant, and Co is the concentration of the electroactive species (mol/mº). 100/100 11 Question 1 of co Attempts Calculate 8, in micrometers, and the current density, J, for the reduction of O, to H, O, at a gold electrode in 0.045 M KOH at 0.60 V vs. SHE at 2.0 x 10² rpm, where D= 2.0 x 10-9 m²/s and v = 3.0 x 10-6 m²/s. Correct 100/100 12 Question 1 of Attempts Correct um 100/100 13 Question 1 of co Attempts Correct A/m2 100/100 14 Question 1 of Attempts Correct

Answer 1

| Answer: Given data is Diffusion coefficient , D = 2-0X10' mis Kinematic viscosity of liquid , v = 3.0x1õm/s Rotalion rate., w = 2.0x10°spm Concentration of electroactive species , Co = ? molim. lie. Co = 0.045 - 0.075 molime. 0-60 For the. Oueduction ne. Oloduction of O of Oy to H2 to Ho, at electrode, the no. of electrons transferred in the half- reaction is 2 electrons. ie. n=2 Faraday constant, F = 4.63x 104 coloumbs Imole. we have to find the i) thickness of this diffusion layer, & is S = 1.610/3 w "2 g / =>8 = 1-61 (2x169) 1/3 (2x103)-1/2 (3x175!46 = 1-61 (1-25X103) (0-104X100/2, (0-5X 17") = 0.70148103-3-1 = 0.4114x colle = 0.7114 x 3-162 x166 2.249x10 m = 2.249 4

Lilly Cuorent demaily, I' is J: 0162.7 03 we'l2 w "Go -) T: 062 (3) (9:63x10') (2x1093? (27.10)" (2x16"). = 0:62. (2) (9-63x19") (1158 1X 17") (1-414x10*%*)(1-27.10) = 2:411 x 104-6+2+1 - 2.411 x 1012 - 2.411 X 3.162 :: J = 7.623 Alma