For each of the following two reactions, predict whether the reaction is spontaneous, under standard conditions, in the direction in which it is written. Calculate Ecell for each. (a) 2 Al(s) + 3 Sn(aq) 2 Al (aq) + 3 Sn(aq) (b) Cd+ (aq) + Cu(s) Cd(s) + Cu (aq)