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Introduction

11 IB CHEMISTRY PRACTICAL DESIGN PROFORMA NAME;......ESTHER..................................................... INSTRUCTIONS A electrochemical cell also called a voltaic cell, it consist of two different half -cells, converting chemical energy into electrical energy using a spontaneous redox reaction as a source of electrical energy. Anode is negative (reduction), and cathode is positive (oxidation). Electron always flows from anode to cathode. There are lots of factors affecting electrochemical cells, this experiment will find out one of the factor affecting the average voltage of electrochemical cells. Aim: To investigate the effect of the temperature change of the anode electrolyte has on the average voltage produced by a voltaic cell with 50ml of 0.5M Zinc sulphate solution and 50ml of 0.5M Magnesium sulphate solution. Hypothesis: As increase the temperature of anode electrolytes, its average voltage will also increase. DESIGN RESEARCH QUESTION: (Is your research question focussed? Does it give precise information like the names of reactants and/or conditions?) How can the temperatures of the anode electrolyte affect the average voltage of electrochemical cells? INDEPENDENT VARIABLE: ...Temperature of the anode electrolyte .......................................................................................................................... DEPENDENT VARIABLE: ...average voltage .......................................................................................................................... CONTROLLED VARIABLES: VARIABLE How it will be controlled Volume of electrolytes Using 50ml of znso4 and MgSO4 in each experiment Concentration of electrolytes Using the same concentration of 0.5M Size of Anode Cut the same size of ...read more.

Middle

Recording data: Those raw data is measured by the different temperature of anode electrolyte and record its average voltage Independent variable Dependent variable Temperature of anode electrolyte (Mg+ MgSO4) Average voltage (v) Uncertainties (v) Observations Trial 1 Trial 2 Trial 3 30�C 0.920 0.933 0.920 �0.002 -MgSO4 and ZnSO4 are colourless, Mg is slivery-white, and Zn is bluish pale grey - when heated, there are little bubble around Mg in the solution of MgSO4 - when temperature rise, the bubble around Mg become more vigorous - The immersion part of Zn metal become light silver, a little bit colour change 40�C 0.917 0.922 0.897 �0.002 50�C 0.889 0.910 0.885 �0.002 60�C 0.883 0.897 0.870 �0.002 70�C 0.877 0.863 0.859 �0.002 Processing data: Processing data given by the average voltage over three experiments based on the different temperature of anode electrolyte (Mg+MgSO4) Independent Variable Dependent variable Temperature of anode electrolyte (Mg+ MgSO4) Average voltage (v) Uncertainties (v) 30�C (0.920+0.933+0.920)/3=0.924 �0.002+ �0.002=0.004 40�C (0.917+0.922+0.897)/3=0.912 �0.002+ �0.002=0.004 50�C (0.889+0.910+0.885)/3=0.895 �0.002+ �0.002=0.004 60�C (0.883+0.897+0.870)/3=0.883 �0.002+ �0.002=0.004 70�C (0.877+0.863+0.859)/3=0.866 �0.002+ �0.002=0.004 Graph: temp VS average voltage Conclusion: The progressing data table and graph show that as increase in the temperature of anode electrolyte, the average voltage will decrease. The results show no evidence to support the hypothesis, the hypothesis may be failed. ...read more.

Conclusion

It can help to control the immersion depth and distance of salt bridge. - The immersion depth of electrode: same as the controlling of immersion depth of salt bridge, mark the certain length of electrode that should be immergerd, and observe the mark change on the electrode to control the immersion depth of electrode. - Reading judgement: take several readings then average them, get the average data from the voltermeter to minizine the chance of judgement. Systematic errors listed above can be accommodated for in the following way. - Temperature control: even if the hot plate will still heat the electrolyte after turn off. In the experiment, when temperature nearly reach the certain value, turn off first, let the remaining heat to heat up the electrolytes, it can minizime the difference between actually temperature and recorded temperature. - The mass change of electrode: the mass change of electrode hard to reduce, because if change the electrode every time, other varibales will alternative have slightly differnce. In order to minizining this errors is repeating its experiment. To avoid the mistakes in future experiments the following modification can be made. - Choose the approxiate instruments, check its percison before using them. - Be aware of limitation of each instruments. ?? ?? ?? ?? ...read more.

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