Emf Lab Report

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Yuxin Qi IB Chemistry HL II Mr. Balakrishnan Nov. 30th. 2013 Factors Affecting EMF of Electrochemical Cell Aim: To find out one or more factors which affects the EMF of the galvanic cell. Introduction: Galvanic cell is a reaction, producing electricity though redox reactions happening on electrochemical cell. The EMF is a shorten expression of electromotive force which is the voltage. Because of the difference in electronegativity between those town metals, redox reaction happens: Zn(s) → Zn2+(aq) + 2e- Cu2+(aq) + 2e- → Cu(s) In the comparison of voltages produced in this experiment, concentration can be determined whether it is a factor or not. Risk Assessment: Due to the electricity produced in the experiment, students should be aware of the dangers and wear gloves which are insulating. Independent Variable: Concentration of ZnSO4 Dependent Variable: EMF of the galvanic cell Controlled Variable: Concentration of CuSO4, Temperature, Pressure and Salt Bridge Material and Apparatus: CuSO4 solution 1mol/dm3 ZnSO4 solution 1mol/dm3 Distilled water Copper Bar Zinc Bar KCl solution Beaker (50cm3) Data Logger Salt Bridge Measuring Cylinder (10cm3, 50cm3) Polishing Paper Procedures: 1. Use 2 separate polishing papers to clean the zinc bar and copper bar and place them appropriately. 2. Use measuring cylinder to get 5cm3 ZnSO4 and add the solution into beaker. 3. Add enough distilled water to 40cm3. 4. Also pick another beaker and add 40cm3 CuSO4 solution. 5. Turn on data logger and connect it to those metal bars. 6. Put salt bridge to those two beakers and record the voltage produced immediately after it gets constant. 7. Write down the record and repeat the trials 5 times, but changing the volume of ZnSO4 added. Data Collection: Trials | Volume of ZnSO4(aq) ±0.5cm3 | Volume of CuSO4(aq) ±0.5/cm3 |

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