Post on 18-Nov-2014
description
http://lawrencekok.blogspot.com
Prepared by Lawrence Kok
Video Tutorial on Factors Affecting potential difference /EMF for a Voltaic Cell and Concentration Cell.
Effect of different metal pairs on the emf for a Voltaic cell
Procedure/Method• Cut metal strips into (1cmx1cm) for Zn, Mg, Al, Fe, Sn and Cu• Polish them with sandpaper• Prepare 1.0M Zn(NO3)2, Mg(NO3)2, AI(NO3)3, Fe(NO3)3, Sn(NO3)2 and Cu(NO3)2
• Pipette 5ml of Cu(NO3)2 into (+) side of well• Insert Cu metal into Cu(NO3)2 solution and connect to (+) side of voltmeter• Prepare Salt bridge by soaking a cotton string in saturated NaCI solution• Pipette 5ml of Zn(NO3)2 into (-) side of well• Place salt bridge shown above• Measure the emf of Zn/Cu voltaic cell• Repeat the steps with different metals pairs shown below
• Compare your results with theoretical values calculated using Nersnt Equation
• Experiment repeated to measure the current produced using different metal pairs
ResultsPotential Difference/V
Current produced/A
Research Questions:• Effect of Different metal pairs on the emf in Voltaic Cell• Effect of Different metal pairs on the current produced in Voltaic Cell
Effect of different metal pairs on the emf for a Voltaic cell
Effect of ZnSO4 Concentration on emf for Zn/Cu Voltaic cell
Procedure/Method• Cut Cu/Zn into (1cm x1cm) and polish them with sandpaper• Prepare 1.0M CuSO4
• Pipette 5ml of CuSO4 into (+) side of well• Insert Cu metal into CuSO4 solution and connect to (+) side of voltmeter• Prepare salt bridge by soaking a cotton string in saturated NaCI solution• Pipette 5ml of 1.0M ZnSO4 into (-) side of well• Place salt bridge shown above• Measure the emf of Zn/Cu voltaic cell• Repeat the steps with different ZnSO4 concentration shown below
• Compare your results with theoretical values calculated using Nernst Equation
• Experiment repeated to measure the current using different ZnSO4 concentrationResultsPotential Difference/V
Current produced/A
Research Questions:• Effect of ZnSO4 concentration on the emf in Zn/Cu Voltaic Cell• Effect of ZnSO4 concentration on the current produced in Zn/Cu Voltaic Cell
Effect of ZnSO4 Concentration on emf for Zn/Cu Voltaic cell
Effect of CuSO4 Concentration on emf for Zn/Cu Voltaic cell
Procedure/Method• Cut Cu/Zn into (1cmx1cm) and polish them with sandpaper• Prepare 1.0M CuSO4
• Pipette 5ml of CuSO4 into (+) side of well• Insert Cu metal into CuSO4 solution and connect to (+) side of voltmeter• Prepare salt bridge by soaking a cotton string in saturated NaCI solution• Pipette 5ml of 1.0M ZnSO4 into (-) side of well• Place salt bridge shown above• Measure the emf of Zn/Cu voltaic cell• Repeat the steps with different CuSO4 concentration shown below
• Compare your results with theoretical values calculated using Nernst Equation
• Experiment repeated to measure the current using different CuSO4 concentrationResultsPotential Difference/V
Current produced/A
Research Questions:• Effect of CuSO4 concentration on the emf in Zn/Cu Voltaic Cell• Effect of CuSO4 concentration on the current produced in Zn/Cu Voltaic Cell
Effect of CuSO4 Concentration on emf for Zn/Cu Voltaic cell
Effect of ZnSO4 and CuSO4 Concentration on emf in Zn/Cu Voltaic cell
Procedure/Method• Cut Cu/Zn into (1cm x1cm) and polish them with sandpaper• Prepare 1.0M CuSO4
• Pipette 5ml of CuSO4 into (+) side of well• Insert Cu metal into CuSO4 solution and connect to (+) side of voltmeter• Prepare salt bridge by soaking a cotton string in saturated NaCI solution• Pipette 5ml of 1.0M ZnSO4 into (-) side of well• Place salt bridge shown above• Measure the emf of Zn/Cu voltaic cell• Repeat the steps with different ZnSO4 and CuSO4 concentration shown below
• Compare your results with theoretical values calculated using Nernst Equation
• Experiment repeated to measure current using different ZnSO4 and CuSO4 conc
ResultsPotential Difference/V
Current produced/A
Research Questions:• Effect of ZnSO4 and CuSO4 conc on the emf in Zn/Cu Voltaic Cell• Effect of ZnSO4 and CuSO4 conc on the current produced in Zn/Cu
Voltaic Cell
Effect of ZnSO4 and CuSO4 Concentration on emf in Zn/Cu Voltaic cell
Effect of Temperature on emf in Zn/Cu Voltaic cell
Procedure/Method• Cut Cu/Zn into (1cmx1cm) and polish them with sandpaper• Prepare 1.0M CuSO4 and ZnSO4 at room temperature (25C)• Pipette 5ml of CuSO4 into (+) side of well• Insert Cu metal into CuSO4 solution and connect to (+) side of voltmeter• Prepare salt bridge by soaking a cotton string in saturated NaCI solution• Pipette 5ml of 1.0M ZnSO4 into (-) side of well• Place salt bridge shown above• Measure the emf of Zn/Cu voltaic cell• Repeat the steps with CuSO4 and ZnSO4 at different temperature shown below
• Compare your results with theoretical values calculated using Nernst Equation
• Experiment repeated to measure the current at different temperature shown below
Potential Difference/V
Current produced/A
Research Questions:• Effect of Temperature on the emf in Zn/Cu Voltaic Cell• Effect of Temperature on the current produced in Zn/Cu Voltaic Cell
Effect of Temperature on emf in Zn/Cu Voltaic cell
Effect of electrode size of Zn and Cu on emf for Zn/Cu Voltaic cell
Procedure/Method• Cut Cu/Zn into (1cmx1cm) and polish them with sandpaper• Prepare 1.0M CuSO4
• Pipette 5ml of CuSO4 into (+) side of well• Insert Cu metal into CuSO4 solution and connect to (+) side of voltmeter• Prepare salt bridge by soaking a cotton string in saturated NaCI solution• Pipette 5ml of 1.0M ZnSO4 into (-) side of well• Place salt bridge shown above• Measure the emf of Zn/Cu voltaic cell• Repeat the steps with different electrode size shown below
• Compare your results with theoretical values calculated using Nernst Equation
• Experiment repeated to measure the current with different electrode size shown below
Potential Difference/V
Current produced/A
Research Questions:• Effect of Electrode Size on the emf in Zn/Cu Voltaic Cell• Effect of Electrode Size on the current produced in Zn/Cu Voltaic Cell
Effect of electrode size of Zn and Cu on emf for Zn/Cu Voltaic cell
Effect of different anion on emf for Zn/Cu Voltaic cell
Procedure/Method• Cut Cu/Zn into (1cm x1cm) and polish them with sandpaper• Prepare 1.0M CuSO4
• Pipette 5ml of CuSO4 into (+) side of well• Insert Cu metal into CuSO4 solution and connect to (+) side of voltmeter• Prepare salt bridge by soaking a cotton string in saturated NaCI solution• Pipette 5ml of 1.0M ZnSO4 into (-) side of well• Place salt bridge shown above• Measure the emf of Zn/Cu voltaic cell• Repeat the steps with different salt solution (different anions) shown below
• Compare your results with theoretical values calculated using Nernst Equation
• Experiment repeated to measure the current with salt solutions shown below
Potential Difference/V
Current produced/A
Research Questions:• Effect of different anions on the emf in Zn/Cu Voltaic Cell• Effect of different anions on the current produced in Zn/Cu Voltaic Cell
Effect of different anion on emf for Zn/Cu Voltaic cell
Effect of salt bridge concentration on emf for Zn/Cu Voltaic cell
Procedure/Method• Cut Cu/Zn into (1cm x1cm) and polish them with sandpaper• Prepare 1.0M CuSO4
• Pipette 5ml of CuSO4 into (+) side of well• Insert Cu metal into CuSO4 solution and connect to (+) side of voltmeter• Prepare salt bridge by soaking a cotton string in 0.5% NaCI concentration• Pipette 5ml of 1.0M ZnSO4 into (-) side of well• Place salt bridge shown above• Measure the emf of Zn/Cu voltaic cell• Repeat the steps with different salt bridge concentration shown below
• Compare your results with theoretical values calculated using Nernst Equation
• Experiment repeated to measure the current with different salt bridge concentration
Potential Difference/V
Current produced/A
Research Questions:• Effect of Salt Bridge Concentration on the emf in Zn/Cu Voltaic Cell• Effect of Salt Bridge Concentration on the current produced in Zn/Cu Voltaic
Cell
Effect of salt bridge concentration on emf for Zn/Cu Voltaic cell
Effect of CuSO4 concentration on emf for Copper Concentration cell
Procedure/Method• Cut Cu into (1cm x1cm) and polish them with sandpaper• Prepare 1.0M CuSO4 and pipette 5ml of CuSO4 into (+) side of well• Insert Cu metal into CuSO4 solution and connect to (+) side of voltmeter• Prepare salt bridge by soaking a cotton string in saturated NaCI solution• Prepare 2 fold serial dilution of 1.0M CuSO4 (0.5, 0.25, 0.125, 0.0625M)• Pipette 5ml of 0.5M CuSO4 into (-) side of well• Insert Cu metal strip into and connect to (-) terminal of voltmeter• Place salt bridge shown above• Measure the emf of Cu 2+(1.0M)/Cu 2+(0.5M) concentration cell• Repeat the steps with different CuSO4 concentration shown below
• Compare your results with theoretical values calculated using Nernst Equation
• Experiment repeated to measure the current with different CuSO4 concentration
Potential Difference/V
Current produced/A
Research Questions:• Effect of CuSO4 Concentration on the emf in Copper Concentration Cell• Effect of CuSO4 Concentration on the current produced in Copper
Concentration Cell
Effect of CuSO4 concentration on emf for Copper Concentration cell
How different metals are used to displace another metal from its salt solution?
Procedure/Method• Cut Mg, Zn, Fe, Sn and Cu into (1cm x1cm) and polish them with sandpaper• Prepare 0.1M Mg(NO3)2, Zn(NO3)2, Fe(NO3)3, Sn(NO3)2, Pb(NO3)2 and Cu(NO3)2
• Pipette 5ml of 0.1M of different nitrate solutions into 6 different wells shown below
• Place a strip of Mg into 6 different wells• Record down all observation on colour change, metal deposit or any metal strip dissolves• Place a √ if any displacement reaction has taken place or X if no visible observations• Repeat the steps with different metal strips and record down observation shown below shown below
Metal strips
Nitrate salt solutions
How different metals are used to displace another metal from its salt solution?
Metal strips
Nitrate salt solutions
Results• Metal higher in reactivity series, displace lower metal from its solution• Mg is more reactive than Cu, able to displace Cu from its solution• Mg → Mg 2+ + 2e (lose e, Oxidation )• Cu 2+ + 2e → Cu (gain e, Reduction )
Observation • Mg metal dissolves• Brown deposit, Cu forms• Blue solution CuSO4 turn pale /colourless
Conclusion Mg > Zn > Fe > Sn >Pb > Cu
Effect of different metals on the rusting of iron
Procedure/Method• Clean 5 pieces of iron nail with sandpaper• Wrap each nail with different metals, Mg, Zn, Sn, Cu shown in diagram above• Place each nail into test tube with 10ml of water• Add 2 drops of phenolphthalein indicator and 2 drops of potassium hexacyanoferrate (III)• Leave iron nail for 2 days and record down all observations in table below
Notes : • Potassium hexacyanoferrate(III) reacts with Fe 2+ producing dark blue colouration• Phenolphthalein – to detect OH- ions, if solution is alkaline it will turn pink
Effect of different metals on the rusting of iron
Results (Mg + Fe) and (Zn + Fe) – No rusting and solution turns pink
(Cu + Fe) and (Sn + Fe) – Rusting and solution turns blue
Acknowledgements
Thanks to source of pictures and video used in this presentation
Thanks to Creative Commons for excellent contribution on licenseshttp://creativecommons.org/licenses/
Prepared by Lawrence Kok
Check out more video tutorials from my site and hope you enjoy this tutorialhttp://lawrencekok.blogspot.com