Chemical Lab Report
INVESTIGATING THE FACTOR AFFECTING THE VOLTAGE OF VOLTAIC CELL
Name: Lim Seong Hseng Date: 20th March 2013 IA CRITERIA ASSESSED: D Declaration: I declare that this report I have submitted is my own original work and I have acknowledged the use of words or ideas of another person.
Introduction Aim: To investigate the factor affecting voltage of voltaic cell. Research Question: How does coupling of different metals from the electroactivity series affect the overall voltage of the galvanic cell? Background Information: The voltaic cell converts chemical energy to electrical energy to generate electricity. There are usually 2 electrolytes used containing spectator metal ions. A salt bridge is used to connect the 2 electrolytes in order to enable the transfer of ions. Circuit is connected from electrode to electrode for mobile electrons to pass through. A galvanometer is always used to detect the electron flow of voltaic cell. The deflection of galvanometer indicates the electron flow of circuit. Electrolyte that has visible color change is always selected. Copper (II) Ion is one of the examples. The presence of such ion will eventually increase the blue intensity of the electrolyte if the concentration of such metal is higher than other metal. Throughout the mechanism of voltaic cell, redox reaction is occurred. The redox reaction gives rise to 2 different half equations. The metal that is placed higher in the electrochemical series is the reducing agent, hence causing electron to loss. This electrode acts as an anode. Conversely, metal that is placed lower in the electrochemical series is the cathode and acts as an electron acceptor. Presence of different variables: Independent variables: Different pair of metals as electrodes Pairs of metals Magnesium and Silver metal Iron and Silver metal Zinc and Silver metal Lead and Silver metal Copper and Silver metal Electrolyte used Magnesium Nitrate and Silver Nitrate solution Iron Nitrate and Silver Nitrate Solution. Magnesium Nitrate and Copper (II) Nitrate solution. Iron Nitrate and Copper (II) Nitrate solution Copper (II) Nitrate and Silver Nitrate solution.
Dependent variable: The voltage across the galvanometer for each metal pair Controlled Variable: 1) Temperature and pressure of the electrolyte- Electrolytes are kept at room temperature and pressure. 2) Volume of electrolytes- 50 cm3 of electrolyte is used for all anode and cathode compartments. 3) Concentration of the electrolytes- Electrolytes solutions are all 1.0M 4) Surface Area of the electrodes were always maintain at 3 cm × 6 cm.
Hypothesis: The potential difference is greater if two metals are more widely placed in the electrochemical series. Apparatus and Chemicals: Apparatus and Chemicals Voltmeter Connecting wires Beakers Silver electrode 1.0 M Silver Nitrate Magnesium electrode 1.0 M Magnesium Nitrate Lead electrode 1.0 M Lead (II) Sulfate Copper electrode 1.0 M Copper Sulfate Salt bridge (Potassium Nitrate) Amount/ Volume 1 2 2 1 500cm3 1 500cm3 1 500cm3 1 500cm3 1 Description 500ml -
Diagram for the experimental setup:
Chemical Equations for each reaction of metal pairs: Pairs of metals Magnesium and Silver metal Iron and Silver metal Zinc and Silver metal Lead and Silver metal Copper and Silver metal Chemical Equations Anode: Mg (s) → Mg2+ (aq) + 2eCathode: Ag+ (aq) + e-→ Ag (s) Anode: Fe (s) → Fe2+ (aq) + 2eCathode: Ag+ (aq) + e-→ Ag (s) Anode: Zn (s) → Fe2+ (aq) + 2eCathode: Ag+ (aq) + e-→ Ag (s) Anode: Pb (s) → Pb2+ (aq) + 2eCathode: Ag+ (aq) + e-→ Ag (s) Anode: Cu (s) → Cu2+ (aq) + 2eCathode: Ag+ (aq) + e-→ Ag (s)
Theoretical value of E° cell: Pairs of metals Magnesium and Silver metal Iron and Silver metal Zinc and Silver metal Lead and Silver metal Copper and Silver metal E° cell E° cell = 0.80 − (−2.37) =...
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