In short, the aim of my experiment is to determine how the concentration of sulphuric acid in solution affects the mass liberated and deposited at copper electrodes, when copper sulphate is electrolysed.
Over all data points, what I observed is that the mass deposited at the cathode was lower than the mass liberated at the anode. Theoretically, the two should be equal, and even experimentally I expected the opposite to be true, due to oxygen production taking place at the anode which could disrupt the liberation of copper. The voltage was kept constant at 3V, so I monitored the current over the duration of the experiment. I observed that the current increased, which further suggested that more ions were released at the anode than deposited on the cathode, as that represents an increase of positively charged particles in solution and thus an increase of current density.
Now, perhaps the liberation of oxygen facilitates the oxidation of the copper anode? Is this my misunderstanding?
Additionally, I was unable to find conditions which would stop the production of hydrogen at the cathode. The voltage required to electrolyse water is 1.23V, but if I set my voltage to that low, no plating took place either. Is hydrogen also expected to be produced alongside the plating process? Maybe, the hydrogen production was disrupting the plating? In that case, what is the explanation for why hydrogen was produced at the cathode in the first place? Since copper is lower in the reactivity series than hydrogen, no hydrogen should be produced.
Can someone point out the flaws in my experiment or where I've misunderstood things. I don't have much experience with electrochemistry. Thank you!