Question

Metallic aluminum can be made by the electrolysis of molten A.O. (a) What mass of N is formed by passing a current of 7.65 A through molten Al., for 3.80 days? The unbalanced chemical reaction representing this electrolysis is shown below. Alo Alto g of Al is formed by this electrolysis, (b) How many minutes are needed to plate out 20.00 g of Al from molten Als, using 7.48 A current? minutes are needed

Answer 1

a) Current , 0 = 7,65 A = 7.65 E (:: 1A=19) Time, t = 3.80 days 24 hr 3600 s = 328320 s Charge transferred, q = cxt =(7.65 )* (3283205) = 2511648 C Thus, the charge transferred in the cell is 2511648C. ------------------------------------- Cathode half-reaction: A13+ (aq) + 3e - > Al(s) Charge transferred in the cell = 2511648C Charge carried by 1 mole of electrons = 96500 C 3 moles of electrons transferred in the cell to deposit 1 mol Al. Molar masss of aluminum (Al) = 26.98 g/mol Amount of Fe deposited by 2511648C of charge 1 mol e 1 mol A1 26.98 g = 2511648Cx 0400 * 96500 C 3 mol e 1 mol Al = 234 g --------------- ---------------------- - b) Cathode half-reaction: A13+ (aq) + 3e - Al(s) Charge carried by 1 mole of electrons = 96500 C 3 moles of electrons transferred in the cell to deposit 1 mol Al Charge required to deposite 10.0 g Fe 1 mol Al 3 mol e 96500 C 20.08% 26.98 & 1 mol Al Imol e- = 214603 C \Current,c = 7.48 A =748 ? (:14=1) Charge transferred, a = 214603 C Charge transferred, q = cxt Time, i = ? 214603 C 7.48 1 min = 28690 sx = 478 min 60 s