Consider the metal deposition reaction M+e M. Suppose the reaction is run at a current density i ...
The exchange current density and the electron transfer coefficient for the reaction Fe e Fee Pt at 25 "Care 2.5 * 10 cm and 0.42, respectively. (a) Determine at what current density to obtain an overpotential of 0.25 V according to the Butler Volmer equation. (b) What will be the overpotential at the same current density according to the Tafel equation?
(i) Plot the current density vs. overvoltage (j vs. h) relationship – the Butler-Volmer equation – for this reaction in the range h = -0.5 to 0.5 V. Assume a transfer coefficient a = 0.5 and vary the exchange current density: j0 = 10-3, 10-6, 10-9 A/cm2. Define the sign conventions for current and overvoltage. (ii) Plot the j vs. h relationship for j0 = 10-6 A/cm2 and a = 0.25, 0.5 and 0.75. (iii) Plot log½j½ vs. h curves...
This is an electrochemistry question.
A nickel plate electrode was submerged in 0.01 M NiSO4 at 25ºC.
Determine the current density when the potential of the nickel
electrode is -0.038 V. Assume the electrode reaction is controlled
by activation overpotential,
= 0.5, the exchange current density i0 = 1*10-5 A/m^2 , and the
activity of Ni2+ is equal to its concentration.
4.4 A fuel cell operates at 60°C and ambient pressure. Exchange current density, io is 0.005 mA/cm. Assume charge transfer coefficient to be 1.0. a) Calculate the activation voltage losses at 1.5A/cm. b) If the resistive losses at 1.5A/cm are 1/2 of the activation losses, calculate the cell resistance, R. c) Assume no concentration polarization losses and calculate cell voltage at 1.5A/cm, at 1 A/cm', and at 0.5 A/cm.
3. The apparatus in Figure I is used for electrolytic deposition of 0.0500 M Cu2 ion from a solution which is buffered to pH 3.00. Oxygen is evolved at the anode at 1.00 atm. E07% = 0.000 V. (a) Given that Ecu 2+/Cu 6 to 12 V de -0.337 V,E:2/H20 7 V, E02/H,o 1.229 V and the internal resistance of the cell is 15.0 Ω. current(A Calculate the potential that must be applied to cause an Voltmeter electrolytic current of...
3. In a heat treatment process, a metal cube of side 2 cm, density 6000 kg/m², and specific heat 300 J/kg.K is heated by convection from a hot fluid at temperature T, = 220 °C. The initial temperature of the cube is T; = 20 °C. If the temperature T within the cube may be taken as uniform, write down the equation that governs the temperature as a function of time t. Obtain the general form of the solution. If...
3.25. In a heat treatment process, a metal cube of side 2 cm, density 6000 kg/m?, and specific heat 300 J/kg-K is heated by convection from a hot fluid at temperature T, = 220°C. The initial temperature of the cube is T; = 20°C. If the temperature T within the cube may be taken as uni- form, write down the equation that governs the temperature as a func- tion of time t. Obtain the general form of the solution. If...
2. In reaction (i), suppose you add 4.0 mL of 6 M nitric acid to a sphere of copper metal that weighs 0.65 grams. Which reactant is the limiting reagent? (Show your work) We were unable to transcribe this image
Problem 13: An electric current is flowing through a long cylindrical conductor with radius a = 0.75 m The current density J=4.5 A/m2 is uniform in the cylinder. In this problem we consider an imaginary cylinder with radius r around the axis AB. Part (a) When r is less than a, express the current inside the imaginary cylinder I, in terms of r and J. Expression: Select from the variables below to write your expression. Note that all variables may not be required. α,...
Pre-Lab Assignment
1) Draw the reaction mechanism for the reaction.
2) Determine the limiting reagent.
Procedure 1 Place approximately 1 g of stilbene dibromide prepared in last week's experiment in a 50 mL round bottom flask. Record the exact mass. Add 0.8 g of KOH and 4 mL of triethylene glycol from the syringe provided in the fume hood (rinse any crystals from the sides of the flask while adding triethylene glycol). 2 Heat the stirred reaction mixture to a...