Determine the molecular mass and identity of a +2 metal, X, that plates 46.3g of X in 6.75 hours at a current of 2 A.

A layer of chromium is electroplated on an automobile bumper by passing a constant current of 40.0 A through a cell that contains Cr3+(aq).  How many hours are required to deposit 151 g of chromium? Note:  Electroplating is the formation of a metal by the reduction of a metal cation.     Select one: a. 32.7 h b. 58.4 h c. 5.84 h d. 3.27 h e. 19.5 h f. 1.95 h

2. Tell whether each of these statements are true and false. If false, rewite it to make it a correct statement. Oxidation always occurs at the anode of an electrochemical cell. The anode of a voltaic cell is the ite of reduction and is negative. Standard conditions for electrochemical cells are a concentration of 1.0 M for disolved species and a pressure of 1 bar for gases. The potential of a voltaic cell does not change with temperature. All product-favored oxidation-reduction reactions have a standard cell voltage E°cell, with a negative sign.

Calculate the concentration of an unknown solution in a concentration cell. A concentration cell consisting of two hydrogen electrodes (P H2- latm), where the cathode is a standard hydrogen electrode and the anode solution has an unknown pH, has a cell voltage of 0.193 V. What is the pH in the unknown solution? Assume the temperature of the solutions is 298 K. !! pH =

1.How many grams of NaCl is present on 5.0 mL of 1.0 % m/V NaCl solution? 2. A zinc bar weighing 3.0 kg is attached to a buried iron pipe to protect the pipe from corrosion. An average current of 0.020 A flows between the bar and the pipe. How many years will be required for the zinc bar to be entirely consumed?

Element A has a standard reduction potential of +0.74V, whereas Element B has a standard reduction potential of -1.15V. Which of the following statements is correct with respect to building a Galvanic cell with these two elements? A. A will be the cathode, B will be the anode, and the cell potential will be positive. B. A will be the cathode, B will be the anode, and the cell potential will be negative. C. A will be the anode, B will be the cathode, and the cell potential will be positive. D. A will be the anode, B will be the cathode, and the cell potential will be negative. E. The anode, cathode, and cell potential must all be experimentally determined.

In an car battery recharging occurs when the car is running by supplying a current to the battery. The reaction that occurs at the cathode in this electrolytic process is   Pb2+  + 2e- -->  Pb (s) If the car supplies a current of 1.50A to the battery, how long will it take in minutes to have 25.0 g of Pb(s) collected at the cathode? Hint: Start with 25.0 g Pb (1A = 1C/sec)  (F= 96500 C/mole e-)  (Pb =207.2g/mol) Answer has 3 sig figs

Zn(s) + 2 H*(aq) → Zn²*(aq) + H2(g) 1. What is the effect on the cell potential of a voltaic cell wi h the above reaction when: The pressure of H2 gas is increased in the cathode. c. Sodium hydroxide is added to the cathode half-cell decreasing the [H"]. а. b. Zinc nitrate is added to the anode d. The surface area of the anode is doubled. half-cell.

3. The Eel fora galvanic cell composed of a Li electrode and an unknown electrode was found to be 2.91 volts. Use the Standard Reduction Potential table to determine the identity of the unknown electrode. Show work. Ered (Volts) -0.80 -0.34 -0.04 -0.76 -0.14 -0.40 -2.37 Half-Reaction Ag (aq) + 1e → Ag(s) Cu²+ (aq) + 2e > Cu(s) Fe (aq) + 3e > Fe(s) Zn²+ (aq) Sn²+ (aq) + 2e +2e → Zn(s) Sn(s) Cd²+ (aq) + 2e* Cd(s) Mg²+ (aq) + 2e Mg(s)

Consider the half reactions in  a cell:  Pb2+   +  2 e ------ Pb(s)  Eo  =  - 0.126  V                                                Fe3+   +   e ------    Fe2+ (aq)  Eo  = + 0.771 V                                    Which of the following statement is correct for the cell?        Given      Given    A. For a Galvanic cell the standard emf will be 0.645 V and Pb will be the anode   B. For a Galvanic cell standard emf will be 0.645 V and Fe will be the cathode     C. For a Galvanic cell standard emf will be 1.668 V and Pb will be cathode   D. For a Voltaic cell the standard emf will be 0.897 V and Fe will be the anode     E. For a Voltaic cell standard emf will be 0.897 V and Pb will be the anode