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Investigate how the rate of electrolysis is affected when changing the current in the circuit.

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Introduction

Electrolysis When chemical compounds are in a molten state, or if they are dissolved in water or other liquids their molecules become "separates into positively and negatively charged components, which have the conduct electricity", or they become ionized Electrolysis is the process of breaking down or 'decomposing' a compound, by running an electric current through a chemical compound when it is ionized. This is done using a simple circuit, as below: z When a pair of electrodes as above is placed in an ionized solution (Electrolyte) and there is a current flowing between them, the positive ions move toward the negative electrode - cathode and the negative ions move towards the positive electrode - anode. The ions that move towards the cathode are called "cations" and the ions that move toward the anode are called "anions". When the ions reach their respective electrodes, they gain or lose electrons and are transformed into neutral atoms. Electrolysis of molten lead bromide: As is above, the ions gain or lose electrons at the electrodes. These reactions can be shown using "Half - Equation". Below, I have shown them using the example of Lead Bromide. The lead bromide is separated into molten lead and Bromide. PbBr(l) Pb(l) + Br�(g) When lead Bromide is melted, the ions are free to move towards the oppositely charged electrode, because Lead Bromide is an ionic substance. When the positive lead ions move to the negative electrode, they gain electrons in a reduction reaction: Pb�+ + 2e- Pb In the same way when the negative bromide ions move to the positive electrode ...read more.

Middle

6) We then repeated the experiment for 2, 3, 4, 5 and 6 amps. 7) we repeated the whole experiment to ensure accurate results. Results: Electricity (amps) (1) Mass of Anode (g) (1) Mass of Cathode (g) (2) Mass of Anode (g) (2) Mass of Cathode (g) 0 1.26 1.26 1.26 1.26 1 1.13 1.43 1.15 1.44 2 0.97 1.73 1.0 1.88 3 0.79 2.14 0.82 2.56 4 0.56 2.62 0.59 2.88 5 0.29 3.13 0.34 3.32 6 0.04 3.84 0.07 3.79 Rate of decrease in the mass of Anode: 1st attempt: Amps Decrease in Mass(g) 1 0.13 2 0.16 3 0.18 4 0.23 5 0.27 6 0.25 Amps Decrease in Mass(g) 1 0.11 2 0.15 3 0.18 4 0.23 5 0.25 6 0.27 Rate of increase in mass of Cathode: 1st attempt: Amps Increase in Mass(g) 1 0.17 2 0.30 3 0.41 4 0.48 5 0.51 6 0.71 Amps Increase in Mass(g) 1 0.18 2 0.44 3 0.68 4 0.32 5 0.44 6 0.47 Graphs: Analysis: The result table clearly shows us that when the current is increased, the rate of electrolysis is clearly increasing. This is shown by the faster increase of mass in the cathode and decrease of mass in the anode. The table below shows a clear pattern of how the mass change goes up in a pattern. The graphs also show us how all our (normal) results go up in an almost straight line, indicating as Faraday's law also states, that the charge is directly proportional to the rate of electrolysis. ...read more.

Conclusion

(2) Mass of Anode (g) (2) Mass of Cathode (g) 0 1.14 1.14 1.14 1.14 5 1.06 1.27 1.07 1.27 10 0.97 1.4 0.97 1.41 15 0.87 1.53 0.88 1.52 20 0.78 1.71 0.76 1.71 25 0.70 1.88 0.68 1.89 30 0.63 1.99 0.6 1.99 Graphs: Analysis: My prediction turns out to be correct. We can see from the tables and the graphs that the rate of electrolysis does not increase or decrease rather it continues steadily in a straight line. This is simply because the ions are constantly moving towards the electrodes, with no factors to increase or decrease the speed. Evaluation: The procedure we used to collect the information we have was quite effective but may have been improved by many factors. We could have repeated the experiments one more time, to absolutely ensure accurate results. Another factor may have been the sale we used when weighing the electrodes. The scale was a very sensitive one, as this was what was required. We also used more than one scale, and any difference between the scales may have caused a strange result. The result was got was what we were expecting, because of the factors that we did not change, and because the experiment was carried out in a suitable manner. My results are fairly accurate, and this time I got not strange results or anomalies. I think we can draw an accurate conclusion from my results as they are quite accurate. Other experiments that could be done in order to draw more conclusions on electrolysis include changing the concentration of the solution, changing the material used for the electrode, the size of the electrode and the temperature of the solution. ...read more.

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