Presentation on theme: "(c) 2006, Mark Rosengarten Voltaic Cells Produce electrical current using a spontaneous redox reaction Used to make batteries!batteries Materials."— Presentation transcript:
(c) 2006, Mark Rosengarten Voltaic Cells Produce electrical current using a spontaneous redox reaction Used to make batteries!batteries Materials needed: two beakers, piece of the oxidized metal (anode, - electrode), solution of the oxidized metal, piece of the reduced metal (cathode, + electrode), solution of the reduced metal, porous material (salt bridge), solution of a salt that does not contain either metal in the reaction, wire and a load to make use of the generated current! Use Reference Table J to determine the metals to use Higher = (-) anodeLower = (+) cathode
(c) 2006, Mark Rosengarten Making Voltaic Cells Create Your Own Cell!!!! More Info!!!
(c) 2006, Mark Rosengarten How It Works The Zn 0 anode loses 2 e -, which go up the wire and through the load. The Zn 0 electrode gets smaller as the Zn 0 becomes Zn +2 and dissolves into solution. The e - go into the Cu 0, where they sit on the outside surface of the Cu 0 cathode and wait for Cu +2 from the solution to come over so that the e - can jump on to the Cu +2 and reduce it to Cu 0. The size of the Cu 0 electrode increases. The negative ions in solution go over the salt bridge to the anode side to complete the circuit. Since Zn is listed above Cu, Zn 0 will be oxidized when it reacts with Cu +2. The reaction: Zn + CuSO 4 ZnSO 4 + Cu
(c) 2006, Mark Rosengarten You Start At The Anode
(c) 2006, Mark Rosengarten Make Your Own Cell!!!
(c) 2006, Mark Rosengarten Electrolytic Cells Use electricity to force a nonspontaneous redox reaction to take place. Uses for Electrolytic Cells: Decomposition of Alkali Metal Compounds Decomposition of Water into Hydrogen and Oxygen Decomposition of Water into Hydrogen and Oxygen Electroplating Differences between Voltaic and Electrolytic Cells: ANODE: Voltaic (-) Electrolytic (+) CATHODE: Voltaic (+) Electrolytic (-) Voltaic: 2 half-cells, a salt bridge and a load Electrolytic: 1 cell, no salt bridge, IS the load
(c) 2006, Mark Rosengarten Decomposing Alkali Metal Compounds 2 NaCl 2 Na + Cl 2 The Na +1 is reduced at the (-) cathode, picking up an e - from the battery The Cl -1 is oxidized at the (+) anode, the e - being pulled off by the battery (DC)
(c) 2006, Mark Rosengarten Decomposing Water 2 H 2 O 2 H 2 + O 2 The H + is reduced at the (-) cathode, yielding H 2 (g), which is trapped in the tube. The O -2 is oxidized at the (+) anode, yielding O 2 (g), which is trapped in the tube.
(c) 2006, Mark Rosengarten Electroplating The Ag 0 is oxidized to Ag +1 when the (+) end of the battery strips its electrons off. The Ag +1 migrates through the solution towards the (-) charged cathode (ring), where it picks up an electron from the battery and forms Ag 0, which coats on to the ring.