Question

Question 8 (2 points) A voltaic electrochemical cell is assembled as described below: Al(s) | A13+(aq, 1.0 M) || Cu2+ (aq, 1.0 M) | Cu (s) The cell potential is initially measured to be 2.02 V. The cell is used to power a small lightbulb, and allowed to remain running for several hours. Using principles of chemical equilibrium, explain what will happen to the amounts of each reagent in this cell as it is left to run, and the effect of these changes on the observed cell voltage while the cell is in use. Your discussion should include any "shifts" in the reaction vs. its equilibrium state. 5 8 - Format B I U

Answer 1

All Abot (ian ll cut (Imolen o u won Oxidation half reaction. at Anode 37 Al Al-ze 0 1 Ethe =-1.67 E 374 2t = 01339 Canthode half reaction . Cut 2d cu Ezt reduction) prog-010 multiplying Eq. ① by 2 and Ea. W by 3 adding them we get and . 2+ 9 Al. + 3 cu B7 2 Alt 3cu a . This is over all cell reaction, Een = (Ecathode Essurde) 2+ 1 or a Eeeu = (0.339 + 1 677) (V) Eeln = 2.016 cel

for this galvanie Now, Nerust equation cell is , E = E - 0.059. log [A 13+) tag [f23772 Cupra od, E = 2:016-0.039 leg to 2,016 v The voltage of this voltaic cell is an indication that the system is out of equilibrium. The Pedon reaction is spontaneously approaching equilibrium.. As time increases concentration of cu decreases in solution and concentration of net increases into solution. 27 Where, IA 3+7) Een = Een - Rat en a (a = ( 2 ) nF Q is called reaction - Quotient

w cathode At Starting reduction potential of cathode is greater than Anode. ( Ep>EL). As time Thereased Ep or, Et decreases and į or Ennode increases, when the reaction reach at equilibrium then E = { and Ecell = 0 At equilibrium Q = k. and Ecell = 0 4 = Equile, Ibrium ( constant) So, at equilibrium the voltage drops to zero and current stops. A battery at equilibrium is a dead battery so as time Puere ases, system try to reach at equilibrium and cell voltage decreases from 2.016 (V) to zero voltage. so the light intensity of the bulb decreases as time increases