Voltaic Cells Tku

UNIVERSITI PENDIDIKAN SULTAN IDRIS

TKU 3023 INFORMATION AND COMMUNICATION TECHNOLOGY IN CHEMISTRY

Assignment: simulation

NAME:

NORHAFIZAH BINTI ABDUL MANAB NOOR FADHILAH

GROUP: LECTURER:

( D20081032342 ) ( D20081032327

BINTI NORDIN ) B PN. ASMAYATI BINTI YAHAYA

VOLTAIC CELLS Teacher’s Guide / Physics Form 4 / Spreadsheets

SCIENTIFIC CONCEPT Electrochemistry represents a subset of oxidation-reduction. Electrochemical cells include electrolytes, electrolyte bridge, electrodes, and an external circuit through which electrons flow. Chemical energy is converted into electrical energy in a voltaic cell. A voltaic cell is an electrochemical device that can produce electrical energy from spontaneous oxidation-reduction reactions. All electrochemical cells have two electrodes; there are a cathode and an anode. Reduction reactions always occur at the cathode and oxidation reactions always occur at the anode. In voltaic cells, the cathode is charged positively and the anode is charged negatively. The identity of the cathode and anode is determined by the relative reduction potentials of the half-reactions that make up the voltaic cell. In general electrons always flow from the anode compartment where oxidation occurs over the wire to the cathode compartment where the reduction occurs. Cations flow from the anode compartment to the cathode compartment over the salt bridge. Anions flow from the cathode compartment to the anode compartment over the salt bridge. Example of voltaic cell:

UNIQUE FEATURE OF ACTIVITY

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Students are able to define and identify, on diagrams of voltaic cells, the anode, cathode, anion, cation, salt bridge and external circuit.

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Predict and write balanced equations for the reactions at the cathode and anode of voltaic cells.

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Students are able to determine and identify, on a diagram of voltaic cells, the flow of electrons, the migration of cations and anions, mass and color changes, and formation of gases and precipitates at the electrodes.

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Define standard reduction potentials and explain how the values are all relative to E°= 0.00 V set for the standard hydrogen electrode and calculate standard cell potential values for oxidation-reduction reactions. ENGAGE

You are given a picture. Observe the picture given.

1. How the things are worked? 2. How can we produce energy? 3. What are the types of energy we have?

EMPOWER 1. Students are allowed to visualize simulation of Copper-Zinc Voltaic Cell •

Elements provided are: copper metal, copper sulfate solution, zinc metal, zinc sulfate solution, and potassium sulfate in the salt bridge, wires and voltmeter.

http://www.youtube.com/watch?v=0oSqPDD2rMA&NR=1

Questions: 1. Explain the reaction for this voltaic cell. 2. The cell reaction involves the following half-reactions: Zn Zn2+ + 2eCu2+ + 2e- Cu

E°red = -0.76v E°red = 0.34v

a) Which element will be the oxidized and which will be the reduced? b) Write the cell reaction. Answers: 1. Zn metal gives up 2 electrons becoming Zn2+ (aq) and goes into the solution and decreasing the mass of the zinc electrode. While Cu2+ (aq) picks up 2 electrons and forms Cu metal on the Cu plate (deposits on the copper electrode) and increasing its mass. Salt bridge allows the flow of ions to maintain equal number of positive and negative charger in the compartments.

2. a) Since 0.76 is larger than 0.34 the Zn will be oxidized. With information given we can conclude that Zn is more easily oxidized. Therefore Cu will be reduced. b) Zn(s) + Cu2+ (aq) ↔ Zn2+ (aq) + Cu(s)

ENHANCE

QUESTIONS: 1. Define the anode and the cathode of the electrode in the cell. 2. What is the function of salt bridge in the cell? 3. State the suitable salt bridge that can be used in this cell.

ANSWERS 1. Anode : zinc electrode Cathode: copper electrode 2. The salt bridge allow ions to flow from the anode to the cathode to maintain equal number of positive and negative charger in the compartments. 3. Sodium sulphate,Na2SO4 / Potassium sulphate, K2SO4