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Investigating a Factor Affecting Mass deposited at the Cathode during Electrolysis

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Investigating a Factor Affecting Mass deposited at the Cathode during Electrolysis Aim The aim of this investigation is to find out what effect the independent variable time or current will have on the change in mass on the cathode, and the change in the mass on the anode. Hypothesis The independent variable I will be investigating will be time, in my experiment I will increase the variable by 5 minutes. I predict that when I increase the amount of time for electrolysis to take place, the mass on the cathode will increase, and the anode will lose mass for every minute electrolysis takes place. My quantitative prediction is that when I double the time the charge will double. I can prove my theory with my scientific knowledge and the equation Q = I � T. 'Q' is the charge which is related to the mass deposited, 'I' is the current and 'T' is the time. So when I keep 'I' and double the time it should prove my prediction correct. Q = I � T Q = 2 � 5 Q = 10 If I double the time 'Q' should double Q = 2 � 10 Q = 20 Because 'Q' is linked to the change in mass, if it is increased the mass will increase on the cathode. ...read more.


Another way I will keep my experiment fair is to keep the powerpack on the same voltage of ten volts, and at the end of each experiment I will takeoff the excess copper on the cathode. To be safe I will use goggles when pouring the copper sulphate solution. To be accurate I will need to use a timer so each experiment can be stopped and started accurately. Another way to be accurate is to use a digital scale, accurate to 2 decimal places. Plan Before we start the experiment we have to set up a circuit that includes a powerpack, ammeter which will be connected in series, stop clock, beaker, filter and electrodes in copper sulphate. Once I have the circuit ready, I need to cut two 5cm long copper electrodes out from a copper sheet and weigh them, once I have weighed them I need to record the weights. After the weighing I will complete the circuit with the copper electrodes and copper sulphate. Then when the circuit is complete I will turn on the powerpack and timer with the help of my partner. Once the experiment is over I will let the electrodes dry off and weight them again and record the results. ...read more.


Experiment 6 is void because the change in mass for anode is -0.09 but the change is mass is +0.44. The graph also allows me to see what has happened in each experiment for example, in experiment 2, I can see that 0.9 grams was lost by the anode but only 0.3 grams was gained by the cathode. This shows me that the rest of the mass was deposited in the bottom of the beaker. Evaluation From my results table and graph, I can see that there were many problems. Firstly time was a huge problem; we did not have enough time in lessons to conduct a 30 minutes experiment. Next time to overcome this I will not use such large time intervals I will use time intervals like 2 minutes. . My second problem was during the experiment the anode simply eroded too fast for the cathode o pick up the copper ions. This made my results more unreliable. To solve this problem next time I will reduce the voltage. I think these two problems let to the results being unreliable, because there are two results that are anomalous. I don't think it was the procedure of the investigation that made the results unreliable, so I would not change the procedure, because I used a timer and digital scale to make the experiments accurate. ...read more.

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